I totally agree with LindaTX, and I think your heart rate is very high for your age when exercising. You need to have your blood pressure checked and have an EKG. Then I think they may get you to do a stress test where you are just wired up to some monitors while you walk on a treadmill, so they can monitor what your heart is doing. I'm sure you know what an echo is, they use it to scan babies in the womb. They may want to do one of those to make sure there are no defects. I am concerned because you say you feel pain in your chest plus the fact that your heart rate is so high. I wouldn't waste any more time, talk to your parents and get an appointment with your GP to explain what's happening. It could be something very simple like your blood chemistry, but it's best not to leave it. Don't be afraid, if you need to ask questions or just talk, please don't hesitate to come here anytime.
Hi Sara and welcome to Medhelp. Its great that you are in tune with your body and concerned about anything that doesn't seem quite right. First of all, you need to talk to your parents if you haven't already and let them know what you're feeling. Also you could talk to your health class teacher. You are probably fine but it would be a good idea to be checked by a Dr. It would set your mind at ease. There are things that can cause your heart rate to go up. Caffeine, as in coffee or soft drinks, some over-the-counter cold and sinus medications, and many more. Your Dr can probably give you a list. Good luck.