HI, I am having sharp stabbing knife like pain right in between my breasts, it is accompanied by shortness in breathing, nausea, and sweating. It lasts about an hour and it has happened to me about 3x in the last few months. I take an antacid chewy and it seems to help. Is this heartburn or something more serious? I don't have numbness in my arms or shoulders, just the sharp unbearable pain that scares the heck out of me, when I try and lay back it felt worse, I also have upper back pain at the same time. Help! I am 40 yrs old, healthy, not over weight.