Christina
What you are describing sounds very much like anxiety to me. Are you going through rought times? I have first hand experience with anxiety. I even went to the ER during one of my first few episodes.
I want to commend you on researching your symptoms. It's great that you are trying to be proactive. The best thing to do is to see a doc. Have you talked to your parents? I don't know your situation, but just to be safe you should get it checked out. Even if it is just stress, there's no reason to accept feeling that way.
To answer your questions, if you have insurance, it should cover the sweat test. It doesn't hurt, they attach little electrodes to give you a small electrical pulse. This makes you sweat. They collect the sweat and test it to see what your level is. Some places you get the result right away, others a few hours or a day or two.
Oh - and if you post this in the families or adults sections, you will get more responses.
Stacey