Hopefully your case is different, but this just reminded me very much of my situation.
Back in November I was up at an inpatient rehab for shooting dope, and everything was going along fine. Anyway, I noticed my breathing was getting more labored by the day, especailly after walking any distance I would be nearly doubled over, out of breath. Long story short, the nurses sent me to the Emergency Room at the local hospital, and after numerous tests and whatnot, they found out I had 2 litres of fluid in my right lung, it wasnearly collapsed. Also I had half a liter of fluid around my heart, which was putting an incredible pressure on my heart. The oxygen levels in my blood were below 55, when they should be twice that. They were amazed I was still walking around. After some more tests and surgery, they noticed I had swollen lymph nodes. A biopsy landed me a diagnosis of cancer. Hodgkins lymphoma. I'm doing chemotherapy now and should be okay, but It was really fuckin' shocking.
I CERTAINLY hope that your situation is something a little less serious. I'm not tryin' to scare you, it just seriously made me think of my situation, and to try and tell people sometimes little things end up being more serious than you may think. It pays to get stuff checked out. I haven't told many people on here about this. Sorry to hijack the thread, it's early and i'm pretty high and rambling.