I'm a little late in replying, but along with everyone else's suggestions, may I also ad panic or anxiety attacks as a guess.
I started having them in high school--I had to "get out" of whatever situation I was in, be it math class, or the dentist. I would experience chest pains, nausea, shortness of breath, sweating, cold hands, shaking and a very distinct feeling that I was going to die. It kept me in the house for a while last year, it was so bad. I had one experience where I almost passed out, but I got outside and didn't.
I pray that it's nothing serious, just your hormones. If it is something like an anxiety attack, they are not all in your head, and hopefully your doc will help you.
Let us know what happens please.