What Could Be The Cause For Chest Pain When All Tests Normal?

Question : I'm a 40 year old nonsmoking white male. Genetic history is a father with RA since his mid thirties. Mother was adopted. Last two years I have had steadily increasing pain in central chest area. No cough, no sharpness or increase corresponding to breathing. More of a constant ache. I notice it more at night, and it's bad enough it does at times wake me up. PCP says lung sounds are normal. Did a cardio consult and got ECG. Everything normal there. Heart is not the problem. Chest x-rays one year ago and again recently, both normal. H pylori negative (I assume, haven't heard from them). I am an x-ray tech and no expert but one rad dictated "enhanced perihilar markings" and my bronchioles do seem to be rather pronounced. I also took it upon myself to check for reflux on an admittedly limited barium swallow. Negative. Recent history: I noticed it about the same time as I started bicycle commuting to work, about 20 miles round trip, average 2-3 times a week. I have laid off at times and taken breaks for the winter time. It seems to hurt more after cardio exercise but lately I am feeling it almost all the time. I swept ceiling tile dust (not asbestos but mineral wool and some fiberglass) for almost ten years in my twenties. This is an area that worries me. Did my increase in physical actively later in life lead to some chronic irritation now? ILD? I haven't been to a pulmonologist yet but am thinking this is my next step. Some guidance please!