So what's wrong with me......?

OK so for the past couple of months I feel like there is some fluid of some sort whenever I breathe. The last time I got a cold was quite a few months ago, and it wasn't severe. I doubt that it is just phlegm in my throat because whenever I cough nothing comes out of my throat, I only feel fluid. When I breathe it feels like something is in my lungs, and I also usually have shortness of breath when doing simple things like going up the stairs or running in phys.ed cl. When I cough though there isn't any blood or strange discolouration, so I doubt it could be pneumonia. I also have painful migraines after school a few days of the week, and I am being treated for swollen adenoids and sleep apnea. What could this fluid-y feeling be? I am 14 if age has to do with anything.