I get a pain in my upper back that spreads around to my chest. Sometimes it lasts about 15 minutes, sometimes 30 minutes. It feels as if I have been stabbed in the back and it comes through my chest. It feels like it comes full circle around my upper body. I have a hard time talking, turn white, clamming and sometimes nauseous. I had every heart test about 3 years ago, but now they are becoming more frequent. What do you think is causing this pain?