I have recurring pain on the right side of my chest that resonates in my back. It's a sharp pain and doesn't always last long. I have it now, the pain's been there for almost 45 minutes now, it won't go away, and that's the longest time i've had it. I mostly have it when I'm angry, in a lot of stress or when I'm doing some type of exercise like ,say, taking the stairs. When I have it during exercise I also experience shortness of breath, and I can feel that my heartbeat is a little irregular. I sometimes have pain in my shoulder on the same side and the pain echoes in my back and goes all the way down my arm, though I don't know it this is related(I carry heavy bags on that shoulder and had some problems with my shoulder bone). So what could it be ? knowing that I'm only 19 years old, and I'm not overweight.