It sounds like anxiety, but even at 17 you can have a genetic heart defect that can cause these symptoms---tell your mom and get to your doctor-- he can do what is called a Thallium stress test--which you just walk/run on a treadmill while they monitor your heart and then inject you with a medicine to take pictures of your heart--that along with an echocardiogram- which is an ultrasound machine that takes a different picture of your heart and an ekg which checks the rhythm of your heart and blood tests will give you a clean bill of health for your heart.

If it is just anxiety-- and I say just -- literally--- because anxiety is harder to fix-- you will need medication to help deal with your stress.

Good luck to you and believe me you are not going insane--you need a good physical--in fact-- your thyroid can cause some of your symptoms as well as a sugar imbalance so tell your mom and get to the doctors---don't do any physical activities until you get checked out.......