You sound miserable. Your problem absolutely warrants a visit to an ENT. Surgical removal of the large mucoceles could help. This might or might not relieve your headaches, but if the sinus symptoms are relieved and the headaches persist, you should seek consultation at a headache clinic at a university medical center. The mucus may be an indication of chronic infection or allergic fungal sinusitis. A good ENT would consider these and order cultures and other tests to identify the infectious organism.
This problem is beyond the expertise of your PCP. You may want to seek consultation at a well known diagnostic institution, such as Mayo Clinic, Johns Hopkins in Baltimore, Maryland or Massachusetts General Ear, Nose and Throat Hospital in Boston, Massachusetts even if you have to travel some distance to do it.
Just thought I would update this. My PCP did send me to an ENT and I actually got in today (due to a cancellation..how lucky am I?!) He did a nasal endoscopy (?), which wasn't much fun. Not terrible, just not fun. He found a polyp blocking my passage into my maxiallary sinus. I now have to have a CT to get a better look at the sinus. He said changing my meds isn't going to help because I am on everything he would put me on. I guess I will find out more in the next couple of weeks. I just want the headaches gone...