I had this problem. Id have other ppl feel my chest bc I was sure they'd be able to feel it; no one could. I got my heart checked out in nuuuumerous ways, everything came out fine--even wore a holter moniter, etc. etc. For me it was definitely anxiety related, or even gas related at times as someone else mentioned, BUT when it was really dramatic, I mean super bad...like...I couldnt turn in bed without it being really bad, I thought something was seriously wrong with me. My cardiologist gave me ativan for my anxiety. Well, ativan made all that mess go away, so...bingo, we know what caused it. Wonderful doc btw. who knew then only way Id relax is if I could see the symptoms dissappear from an anti-anxiety. I don't notice it anymore btw, if it happening.