What Causes Burning Sensation In Left Breast?

My left breast is having a burning nawing pain. It feels superficial in my breast not chest. I do not have any shortness of breath but I do have pain coming frommy left shoulder blade around to my left breast. It feels like a musclespasm. I am 43 yr. Old female who had a nnuclear stress test done in Dec. 2014 and it came back normal. I also feel like it to s hard to swallow even water especiallyfirst thing in the morning