CBT is a effective way of reducing your anxiety, breathing exercises, distraction techniques, realxation exercises, meditation and realising anxiety can not hurt you in any way helps. All of the above are methods used in CBT and when done everyday can reduce anxiety to a piont that you will be able to live a normal life.
You did know that med school was going to be a rather intense experience, right? Why do I get the feeling all this stress/tension/anxiety is coming as something of a surprise to you? Have you talked to any of your fellow students about how they deal with the stress? I can promise you that you're not the only one freaking out.
There are many ways you can deal with the tension without drugs. Talk therapy. Yoga. Meditation. Adequate diet and exercise. Massage. Accupuncture. Tai Chi. Personally I think being open and honest with your fellow students is your best bet. Befriending people going through the same experience you are, talking freely and openly about your fears and all the tension you're feeling will go a long way to make you realize you're not alone...........which creates tension of it's own.
I'm sure you have a faculty advisor. If you can't bring yourself to talk to anyone else, this person would be the one I went to.
Good luck
Greenlydia