Puzzled

[Essence641]

Back in November 2007, I admitted myself into the hospital.  Had worked an eight hour shift. After working,I had shortness of breath, tightness in my chest and pain on my right side.  Xrays, doplers, MRI, and several blood draws later, to this day, the doctors cannot tell me what the problem is.  The diagnosis was pleural effusion, however, they ran every test from lupus, Rheumatoid Arthritis Factor, CRP, etc etc.  Needless to say, I was very frustrated by the situation.  About $2000 plus later in medical bills, still no answer.  I have pretty much given up looking for the answer, but if I can get some type of insight as to what may have caused this problem that would be wonderful.  

I have recovered, however, I still have some shortness of breath.  I don't smoke.  I don't do drugs nor play heavy contact sports, need to lose about 50 pounds, nothing else.  Suggestions?