Is This A Heart Or A Back Problem ?

Every few days, I get this... spiralling numb pain on the left side of my back, just around my shoulder blade . It feels like someone is taking their hand and digging their fingernails into my back in a circular pattern, and it also feels like pins and needles. Today, at work, it started doing that, and it started hurting a lot. Then, I started sweating and I felt really hot, and the pain got so bad that my vision started going a bit blurry and I couldn t focus on what I was doing. It started feeling like there was something wrapped around my body, pushing on my chest from all directions, and restricting my ability to breathe. I tried to ignore it and concentrate on what I was supposed to be doing, and it went away after about twenty minutes, although the pain/ numbness in my back keeps coming back. Is there something wrong with my heart or my back? I wasn t stressing myself at work, or doing anything strenuous. I was counting stock.