What Causes Pain Under The Breasts Radiating To The Back?

Hello, i got a few questions about heart attack. I been having pain in the left side of my chest under my breasts for the pass two days. On top of this today it has gone to the left side of my back. Earlier it was on the left side of my neck and it is only on the right side of my neck alone ear to my neck a discomfort pain. If I stand up i'm not so much pain. I do have night swell a few times a week. I did have two attacks back in Dec. 2011. My husband thinks it is a pull muscle. Is this something I should want to go to the ER to be check out? Thanks Tanya