oh my gosh I had exactly this happen to me - I was so panicked I called the midwife and she said call my doctor. THe doctor said that it was most likely a muscle thing some kind of reflux that happens when things get all pushed up inside you, somethign to do with where the food goes or something I think? Anyway I was still really freaked out cos I was convinved I was having a heart attack cos the pains were so sharp and severe and right in my chest that I just couldnt picture them being muscle pains, so my doctor sent me for a ECG just to be on the safe side, and it came back all fine, no heart problems no sign of heart attack. COULD HAVE FOOLED ME THOUGH, I WAS CONVINCED I WAS HAVING HEART ATTACKS! They did tell me that the signs to look out for are shortness of breathe and sweating and pains in your arm - and the pain of a real heart attack isnt short and sharp, it is much longer. My pains were short and sharp (and really severe) but none of the other stuff happened.
Anyway yours might be the same thing, but all the same they say with chest pains it is always good to consult a doctor, but just thought I would share what happened with me to put your mind at ease.