Sudden, repeated one-sided pain behind the eye and over the parietal scalp should be assessed urgently today, particularly if this is new for you. Go to an emergency department now or call emergency services if the pain was instantly maximal, is the worst/new type of headache you have had, or keeps recurring.

Seek emergency care immediately if there is blurred/double vision or vision loss, a red eye, nausea/vomiting, weakness/numbness, facial droop, speech difficulty, confusion, fainting, fever/stiff neck, eyelid drooping, unequal pupils, or pain following injury. Sudden severe headache and eye symptoms require urgent assessment, as noted by the NHS headache emergency guidance and NHS eye-pain advice.

Attacks lasting 15-20 seconds can occur in some primary headache or facial-pain syndromes, but new sudden retro-orbital pain can also rarely signal eye, blood-vessel, or neurologic conditions that cannot be ruled out safely online. Do not assume it is migraine or stress.

Until assessed: do not drive yourself if symptoms recur or vision is affected. Note the exact onset time, number of attacks, triggers, eye redness/tearing or nasal blockage, and any neurological or visual symptoms, and tell the clinician.