This has been happening for a few weeks now. I am 15 years old. At least once in every day (even when sitting down) my heart will race to a speed of that of a half-note and it will hurt sorely with each pump. I can also feel one of my back ribs aching as well. What could this be? Should I see a doctor? I have a feeling it may be related to the fact that I have been drinking like at least 5 cans of pop each day for a while.