I cannot diagnose this safely from these symptoms, but one-sided facial swelling with fever needs urgent in-person assessment today, especially if it is painful, red, warm, near a tooth, jaw, eye, or nose. Causes can include a dental abscess, sinus infection, salivary-gland infection or blockage, or facial skin infection. These infections can spread and sometimes need drainage and prescription treatment. NHS guidance on facial swelling notes that facial swelling with fever may indicate an infection.

Go to an emergency department now if any of these are present:

Brown menstrual blood is often simply older blood and can occur at the start or end of a period. But if pregnancy is possible, do a pregnancy test today. Brown bleeding can occur in pregnancy, and bleeding plus one-sided lower abdominal pain, shoulder-tip pain, dizziness, fainting, or heavy bleeding requires emergency care because ectopic pregnancy must be excluded. See the NHS ectopic-pregnancy symptoms and pregnancy bleeding guidance.

An increased RBC count on a blood test does not by itself explain the facial swelling. It can be temporary, for example from dehydration during fever, but persistent elevation in hemoglobin/hematocrit needs a clinician to review causes such as smoking, sleep apnea, lung/heart conditions, high altitude, medicines, or rarely a blood disorder.

Take the lab report with you and arrange same-day evaluation at urgent care, a doctor, or a dentist depending on where the swelling began. Do not squeeze the swelling or start leftover antibiotics.