Thanks for the info. I'm going to ask about a fungal infection. I had sinus issues for a LONG time (no fever until my 3rd root canal, same tooth) until the dentist discovered an abscessed tooth. I was shocked that the sinus CT scan didn't show anything but the scans by the endodontist (specialized scans) actually showed missing bone where the infection had eaten through it. I even developed a "sinus tract" where the infection caused a pathway into the roof of my mouth (have a bump there). My ENT treated me for allergies, sinus migraine, etc. If you have cavities, filling or caps on any back upper teeth you may want to consult an endodontist who can rule out dental caused sinusitis (before having surgery). Hope you get straightened out soon.