I am 19 year old female and has been having some weird feeling in the left side of my arm. I had went to the doctor a couple months ago because I had pain in my left breast and behind in my lower shoulder. My doctor said that it was a pulled muscle. I started up at a gym and the pain seemed to go away but now I've been having this tingling feeling from my left elbow all the way into my hand and fingers. Sometimes I've noticed it in my upper arm but not as much as from my elbow to fingers. I am worried because I don't want it to be a heart attack or something. I am on birth control and was also wondering if this could be an affect from it. Or if it is just a pinched nerve?

Anyone have any ideas?