Wheezing problem

[rob7]

A few months ago I returned from a deployment and noticed that I was sometimes wheezing at night and after exercise. It doesn't happen to me all the time just every now and then. I also have post nasal drip which is pretty much constantly going on. I've been to the doc a couple of times and at first they said it was bronchitis, then they thought it was a lingering effect of the flu, and now they are saying allergies.

I can still put out and complete strenuous exercise but it just annoys me and I want to get rid of it. Does anyone have any idea of what this could be or medications to treat it? Also, is it possible that the post nasal drip is causing the wheezing in my throat and that it isn't in my lungs?

Update: I've been doing a lot of research here lately and think I may have sinusitis because of the constant post nasal drip and congestion. I also get a weird smell in my nose sometimes (hard to explain). Anyway, I was thinking the post nasal drip from the sinusitis may be causing the wheezing.

Does this sound feasible?

Thanks for your time and answers.