Constant Chronic Left Sided Chest Pain?

I have had constant burning chest pain for over a year now and I mean constant, no breaks whatsoever. Its in the center just about a inch to the left. I have had every test imaginable, ekg, echo, nuclear stress test, cardiac cath, ct scans, blood work .. everything has come back fine. It is getting worse and almost unbearable, I always feel my heartbeat all the time sometimes it feels like it thumps in my chest real hard. I have no stress in my life except for wondering what this could be. It hurts so bad that I sometimes just break out in a sweat. The pain never leaves me and I don't know what else to do. I have no insurance so I cant afford the Pain Dr that they want me to go to. Anybody have any idea as to what this could be. I am so miserable and it hurts and its affecting my quality of life. I just want answers and the Dr's don't seem to have any except maybe nerve damage but no explanation how this could of happened.