My heart does this thing. It will be beating regularly, then suddenly it will beat a real hard pound, then it feels like a drum roll, then two more real hard pounds, then it feels like it skips a couple beats, then back to normal. This leaves me feeling like I m out of breath, but I m not and it exhausts me for about 2-3 minutes. What is it doing? And sometimes my left arm will hurt, and it has gone numb a couple of times. Am I headed for a heart attack? I m 58.