As for the elevated heart rate, chest pain and shortness of breath: if this was the very 1st time you experience such signs and symptoms, and they were short-lived and self-limited, then I would not worry much about them. If, however, these signs and symptoms have occurred previously or are happening frequently, then you need to consult a physician in order to investigate them. Possible causes include anemia, hyperthyroidism (overactive thyroid gland), and anxiety; coronary artery disease (which leads to heart attacks) is highly unlikely seeing your young age and assuming that you are otherwise healthy.