suggestions as to what's going on?

[dragonfly054]

Hi-

For a couple of years, I've had an annoying on-again off-again frog in my lower throat, along with an (also on-again off-again) sensation of a bit of rattle-y phleum.  The phlem is located behind my sternum, maybe an inch or two above the ziphod process.  That seems to be being produced at about the location where the bronchial tubes are branching of from the trachia.  The mucosus there is firmer, and hard to loosen, alshough I try because it is annoying.

I've had times where there was soft mucous that I couldn't quite lossen up enough, and could barely talk for a couple of minutes.  Lately, the lower, rattle-y mucous seems to be getting worse, and I have been coughing (a non-productive cough).  Also, sometimes my lungs feel a bit like I've been exercising hard when I haven't been exercising at all.

I don't smoke, come in contact with second hand smoke or any other known air polllutants, or have any known allergies.

Any suggestions what might be the cause, and what I could do about it?  

[dragonfly054]

One more thing about my above questions.  When I do produce mucus, it doesn't seem to be discolored, more of a white or maybe very very pale yellow tint.