I can partially agree with your doctor when she says the problem is not in your sinuses. I agree because any problem that ends up in your sinuses always has to come from somewhere else, a foreign agent always has to be introduced for there to be a problem. But I do not agree because you are reacting and thus the problem that is now in your sinuses should be treated. I can guess what the problem is, even if the true problem is going through to your lungs and after that is effecting your sinuses.
What I think is happening is you're breathing in a lot of horrible particles that are then affecting your body, thus what you need to do is cut down on these particles that you are reacting to. How you do this is you should get an air filter that will take these out of the air for you and then you won't be ingesting them to your detriment.
A colleague of mine told me about this problem with air quality back when I was struggling with it, but did not yet understand what it was linked to. She told me then about Polarized Media Air filters and that I should look them up. I did the research and found that they work quite extraordinarily. They actually create a static field around the filter that attracts the particles to the fibers. It's quite an efficient design and I found it worked very well on my own problems.
The best place for price that I've found is at www.airlifeone.com. I'd further recommend that you look for the Electrobreeze brand as it is cheaper, and there's essentially no difference between it and the other brand.
Well, I hope that I've been able to help you both out.
I am suffering from the similar problem. in my case I dont have asthma but do have post nasal drip issue. I produce a lot of white sticky mucus which is only clear white in color and also have breathing difficulties at time. My ears recently started to hurt on both sides and seema like they r swelling up as well.. I think i have sinus problem but not sure because my nose stays stuffed up all the time..in ur case its been on for 4 years but i just discovered it..My doctor also told me i have hyperexpanded lungs but i fail to c y , this mite b your problem but i am not sure. Since your lungs cant get rid of the trapped air in your lungs it can produce mucus but every case is diffrent. I am only 21 and have this problem. but talk to your doctor and go thru a few x-rays to b sure of the root cause of your problem.Thx