The key insight: this is not two different lesions, it's one cord lesion at two different stages of "spinal shock"

• 0-24 h: areflexia/hyporeflexia, no plantar response yet
• Day 1-3: cutaneous reflexes return, deep tendon reflexes still absent
• Day 4-30: deep tendon reflexes recover, and importantly, "the recovery of the Babinski response closely parallels the return of the ankle jerk reflex" (Bradley and Daroff's Neurology in Clinical Practice)
• 1-12 months: full spastic hyperreflexic picture

Localizing the lesion

• Face spared, both upper and lower limbs involved → lesion has to be in the spinal cord itself, at or above the cervical enlargement (cannot be higher, since cranial nerves are untouched).
• Bilateral but strikingly asymmetric (near-hemicord pattern, worse left) → this is what textbooks call a "Brown-Séquard plus" pattern rather than the textbook-pure Brown-Séquard syndrome. Classic Brown-Séquard gives you dissociated sensory loss (ipsilateral proprioception/vibration loss, contralateral pain/temperature loss one to two dermatomes below the lesion) - your patient instead has more or less global sensory loss (both touch and pain) on the more affected left side, which is the "plus" variant: "asymmetrical hemiplegia as well as hypoalgesia more prominent on the less paretic side" is the real-world rule, pure Brown-Séquard "rarely occurs" (Rosen's Emergency Medicine).
• No trunk sensory/motor deficit and preserved ability to roll over is a bit unusual for a fully transverse lesion (you'd expect a sensory level), and may simply reflect that the lesion is still evolving/incomplete rather than a complete cross-sectional myelitis.

Differential diagnosis you should be working through

1. Spinal epidural abscess / discitis-osteomyelitis - this is the one you cannot afford to miss. The textbook triad is fever + back pain + progressive neurological deficit, and importantly the full triad is present in only 8-37% of cases, so its absence doesn't exclude it (Tintinalli's Emergency Medicine; Harrison's). A febrile illness a week before, even if it "settled," can represent untreated bacteraemia that seeded the epidural space, with pain and cord signs appearing later as the collection expands and compresses the cord. This needs an urgent contrast MRI of the whole spine and, if found, emergency neurosurgical decompression plus antibiotics - it is time-critical.
2. Acute transverse myelitis (para-/post-infectious, immune-mediated) - fits well: presumed autoimmune, "deficits...typically bilateral but may be asymmetrical," triggered days to weeks after a febrile/viral illness (Bradley and Daroff's Neurology in Clinical Practice).
3. NMOSD / MOG-antibody disease - can produce longitudinally extensive, painful, asymmetric cord lesions; worth checking AQP4-IgG and MOG-IgG.
4. Spinal cord infarction (anterior spinal artery or sulcal branch territory) - classically presents with sudden severe pain at the level of the lesion followed by rapid (minutes-to-hours) flaccid paralysis, which matches your timeline quite well. Ask specifically about vascular risk factors, and don't casually dismiss the neck massage - if there is any possibility of vertebral artery injury/dissection from neck manipulation, that's a distinct mechanism for cervical cord ischaemia and worth asking about directly (any neck trauma, hypertension, clotting tendency).
5. Tuberculous myelitis / Pott's spine with cord compression - relevant to keep on the list in an endemic setting, though it is usually more subacute than this presentation; a recent systematic review is available if you want to read further (PMID 40102389).
6. Less likely but worth excluding: viral myelitis (HSV/VZV/enterovirus, or regionally relevant arboviruses given the antecedent febrile illness), and an atypical GBS variant - though the presence of a clear Babinski sign argues against pure GBS, which should give you absent reflexes and no extensor plantar response.

What would settle it

• Urgent contrast MRI of the whole spine (cervical to lumbar) - the single most important next test. It will tell you cord signal change, length of lesion, presence of enhancement, and crucially whether there is a compressive collection (abscess) that needs surgery instead of steroids.
• CSF analysis - cell count/differential, protein, glucose, oligoclonal bands, viral PCR panel, and TB workup (ADA, AFB, GeneXpert) if the MRI supports it.
• Blood cultures and inflammatory markers, since the story starts with an unexplained febrile illness.
• AQP4 and MOG antibodies if myelitis is confirmed and no compressive cause is found.
• Bladder/bowel and anal tone assessment - you didn't mention this, and it matters both diagnostically and for immediate catheter care.

Why clubbing changes the picture

1. Subacute infective endocarditis (IE) with septic embolization to the spinal cord - leading hypothesis

• Clubbing occurs in roughly 10-20% of infective endocarditis cases (Harrison's Principles of Internal Medicine), classically in the subacute form that has been smouldering for weeks before the patient presents dramatically.
• Neurologic manifestations occur in 20-40% of IE (Harrison's) - most commonly embolic stroke, but septic emboli can also lodge in the spinal cord's segmental/radicular arteries, causing spinal cord infarction, microabscess, or a septic myelitis. This would explain the abrupt, severe pain (infarct pain) followed by rapidly evolving, asymmetric, initially flaccid deficit exactly the way it happened here.
• Embolization of infected material can also cause meningoencephalitis or a parameningeal inflammatory reaction, which would produce the CSF pleocytosis you found, even without the CSF necessarily growing an organism (Bradley and Daroff's Neurology in Clinical Practice).
• The preceding "fever with back pain a week before admission" fits a bacteraemic phase, possibly with an early vertebral/discal seeding, before the dramatic cord event.

2. Tuberculous meningomyelitis (Pott's spine / TB radiculomyelitis) - strongly consider in this setting

• Classic CSF picture in TB meningitis: lymphocytic pleocytosis (10-500 cells/µL), high protein, low glucose, raised opening pressure (Harrison's Principles of Internal Medicine). If your patient's CSF is lymphocyte-predominant with high protein, this becomes much more likely than a bacterial process.
• Clubbing, while not classically taught as a TB sign, is well described with chronic pulmonary TB, bronchiectasis, or empyema - so if she has chronic unrecognized pulmonary disease, that would explain both the clubbing and predispose to haematogenous or CSF-spread cord involvement (tuberculous radiculomyelitis, arachnoiditis, or a spinal Pott's abscess causing compressive myelopathy).
• The subacute-on-chronic pattern (weeks of low-grade illness before an acute deterioration) is very typical of TB.

What actually differentiates these two

Bedside things to check right now on the patient

• Auscultate for a cardiac murmur, look for splinter haemorrhages, Osler's nodes, Janeway lesions, check for splenomegaly and fundoscopy for Roth spots (IE workup)
• Chest exam for crepitations, bronchiectatic changes, cavitary breath sounds and ask about chronic cough/haemoptysis/weight loss (TB/bronchiectasis workup)
• Look at the fingers again carefully - is this clubbing alone, or is there cyanosis too (raising congenital cyanotic heart disease with paradoxical embolism as another explanation for both clubbing and an embolic cord event)?

Investigations to send/confirm

• Blood cultures x2-3 before or independent of antibiotic timing
• Echocardiography (TTE, escalate to TEE if suspicion remains high and TTE is negative)
• Contrast MRI whole spine (if not already done) - looking specifically now for a cord infarct, an intramedullary abscess, or a Pott's spine/paraspinal collection, not just a "myelitis-looking" T2 hyperintensity
• CSF: cell differential, protein, glucose, Gram stain, AFB/CBNAAT, culture
• Chest X-ray/HRCT chest looking for bronchiectasis, cavitary TB, or an underlying cardiac silhouette abnormality
• ESR/CRP, and if IE suspected, apply the modified Duke criteria once culture and echo results are in

Why 39F changes the odds

• often presents as a longitudinally extensive cord lesion
• commonly shows CSF pleocytosis and/or elevated protein (Firestein & Kelley's Textbook of Rheumatology)
• can be the initial manifestation of SLE, occurring even at low overall disease activity
• is frequently associated with antiphospholipid antibody syndrome, which causes a thrombo-occlusive (vascular, infarct-like) mechanism rather than pure inflammation - this would elegantly explain the sudden severe spinal pain followed by an abrupt, infarct-pattern, asymmetric myelopathy, on top of the inflammatory CSF pleocytosis

Updated priority list for this patient

1. Infective endocarditis with septic spinal cord embolization (fits clubbing, CSF pleocytosis, fever, and now the demographic if she has underlying rheumatic mitral valve disease) - confirm with echo + blood cultures.
2. SLE-associated (± antiphospholipid) transverse myelitis - fits age/sex, CSF pleocytosis, and the abrupt vascular-type onset - confirm with ANA/dsDNA/APLA panel and MRI pattern (longitudinally extensive lesion).
3. Tuberculous meningomyelitis / Pott's spine - still very relevant in this setting, confirm with CSF lymphocytic picture, ADA/CBNAAT, imaging for vertebral involvement.