I'm almost 16, and have been running cross country for the pass two months. Since school my stress levels have skyrocketed, sleep has been minimal to non-existent, and the other day I was told my worse fear was a reality. Due to cramps in my legs, I take bathes in Epsom salt religiously. Since Thursday of last week my pulse during practice has been high enough to worry my coach, I'll get the feeling of my heart in my throat, and yesterday I got a scary tightness in my chest. Today it's come back with the weird feeling in my throat, but at like easy things like going up stairs. What could it mean?