I'm currently recovering from a sinus infection, and last night (after ~4 days on antibiotics) I had what seemed like an allergy attack (head filling up, hives, intense itch), leaving what feels like a head full of liquid (still feels the same). Strangely enough there's no nasal congestion, practically no ear congestion, and little to no drainage either. I have heard about brain swelling, but I've never had any head trauma. Is this normal? And what do I do to make it drain/provide relief?