This sounds like a continued problem with your sinuses. I would get another CT scan when you are having these symptoms to see what is going on in the sinuses. There is no other way to evaluate whether there is an infection or blockage without such a test. It is also possible that you may have a chronic fungal infection in one of the sinuses that flares up on and off. An antifungal is needed to treat this. It takes a special type of culture to determine. Seeing your ENT is the place to start in this process.