It is possible that if the problem has occurred after flying with no problems that you have suffered a sinus barotrauma. Equalisation problems can pull the lining of the sinus away from the bone and cause one of several problems. One, it may not re attach and as it's a mucus membrane, it can then be over active. Second, it may not gow back properly and a growth, or 'polyp' may obstruct the opening. Last, it may get infected.
An ENT specailist is your best solution.
As an aside, I know a guy who doesn't have sinuses. It occurs in a very small percentage of people apparently. Lucky guy!