@jessicamt Your symptoms sound unusual for such a young person. Are you sure they are not caused by anxiety or stress? I had a friend who was very stressed due to school and exams and actually went to the ER thinking he could be having a heart attack but it was diagnosed as stress, and sure enough when exams were over he was fine. Do you find that there is anything going on in your life at the times when these attacks occur? Are you having family stresses? Also, exhaustion is often due to depression, or perhaps it's from SAD (seasonal affective disorder). If that, it should improve now that the days are getting longer.
If not you definitely need to be more insistent about seeing the doctor. Are your parents concerned? Could they advocate for you? Unfortunately, they would probably be taken more seriously than a teen would. I would definitely not want my daughter to be going through this. Please make your parents more aware of just how serious these attacks feel and ask them to help you.