Why I do I still have pain in my sinuses 5 weeks after FESS surgery?

Discomfort to the sinuses after sinus surgery is common.  Discomfort tends to be limited to just a few days after the surgery up until about 7 to 10 days afterward.  Discomfort is significantly remedied by endoscopic assisted sinus cleaning called "debridement". During surgery the sinuses are opened, but immediately become clogged again with debris, scabs, mucus, and dried blood.  With debridement the sinuses can reopen and the discomfort diminishes.  When discomfort persists after sinus surgery, a common cause is persistent clogging of of the sinuses, and/or sinus infection.  

usually the chronic pain from sinusitis and the postop pain are gone or vastly improved by 2-4 weeks postop. It takes about 4-6 weeks after surgery for the sinus lining to recover to the point where it is now cleaning itself and for the swelling around the sinus openings after the surgery to resolve.  My experience has been that postop infection can double the healing time.  I suggest that you visit your surgeon to see if there is still infection and to get bacterial cultures, and to assess the sinus openings to see if they're patent.  If there were polyps then oral steroids are often necessary with antibiotics to reduce the sweling.  Hope these suggestions help