For the past week, my legs, particularly from the middle of my legs down, have been feeling like I've been having bricks in them. With physical activity, they begin to feel weak and spasm, making me fear a possible blood clot or impending heart issue. This morning, while and after dancing, I experienced dizziness and lightheadedness, almost fainting. It ceased within a few minutes of stopping the activity and laying down, but I've also been having left arm pains as well. They are short, but worry me. After eating today, I felt the middle of my jaw [middle of the bottom row of my teeth] throb for no apparent reason and I fear that something's going to happen soon. Jaw pain is pretty atypical of my usual pain. I do usually have sinus issues, but random throbbing in my jaw is not one of them. Is there any way for me to relax and not fear the heart issues? I'm 16, with no family history of heart issues, last EKG was almost a yr. ago....?