I'm 20 w/no prior health probs. Suddenly my heart started racing, my chest was heavy. what could it be? Also, I was not anxious or nervous, I was trying to go to sleep actually. I went to a doctor who didn t see anything to immediately serious but he refered me to a cardiologist just to be sure. I feel pretty good now, but still a little odd. My chest doesn t hurt or anything but it doesn t feel normal either. It s all a little freaky to me.