Hi.. this is the first time I've posted here.

For the last month or so, there has been an on-and-off again feeling in my mid-upper chest, usually on my left side. The best I can describe it is as a sort of non-painful tightness, or soreness, I guess. It is always fleeting, and very sporadic. I never know when it’s going to “act up”. It feels sort of the way a sore muscle does, and sometimes it just feels like digestion. I thought it might be heartburn, but I looked up the symptoms of heartburn on Web MD and it said that it's "a feeling of burning, warmth, heat, or pain that often starts in the upper abdomen just beneath the lower breastbone". None of those feelings are really what this is, and I often feel it higher up in my chest than the "upper abdomen".

I saw a doctor almost a month ago, right after I started feeling it, and he checked me out and said I’m totally healthy as far as my heart and lungs are concerned, but he didn’t say what this was, either.

If you have any thoughts on what this might be, if it’s anything, or what I can do about it, I’d appreciate to hear them. Thanks for your time.