I am not sure if it was your post inquiring about
this before Lovelabs but a few of us mentioned that it could be costochondritis. I think Cajungirl has this also. When I have a flair up, it feels just like my heart and sent me to the ER on two occasions with them keeping me for a few days as my BP goes way up. After numerous cardiac work-ups, all ok, the diagnosis was costochondritis. It is an inflammation of the cartilage and that is why you feel it in the ribs, chest, back and also when breathing. Google it and you will see that it says the pain can be "severe." But, certainly if you feel it may be a heart issue, have it checked out by all means. Good luck D