I have chest wall pain, and it goes to my breast--what could be causing this?

Muscle spasm: You have two big flat muscles in the chest -- the pectoralis muscles. If they spasm, it causes very intense, sharp stabbing pain, which can go to your breast. Comes and goes, might be brought on by using your arm/back/abs on that side. Massaging your chest (just like rubbing a charley horse out of a calf spasm) can help. If this occurs with exercise, eating, strong emotion --> check out heart.

Multiple things: Could be a problem with skin, nerves, muscle, shoulder, lung, heart, or stomach. See your doctor for a more thorough history, physical exam and further evaluation. If you sleep on your stomach you could have a neck strain that radiates pain to the chest or arm. Get checked out just to make sure.