I have recurrent headaches after endoscopic sinus surgery. what should i do?

Talk to ENT: I would certainly talk to your ent. This may be as simple as a new sinus infection, but it could be a complication from the surgery.

Tell your surgeon: If you haven't already, you need to discuss this with your surgeon. Headaches can occur following any operation including endoscopic sinus surgery. There are certain things about sinus surgery which can lead to obstruction and headaches or persistent infection. If you have discussed this with your doctor and you're not getting anywhere seek a second opinion.