Go to college. Be smart about it and go to a state university, unless you can get a scholarship for a more expensive one. Take loads of science and math. Major in Pre-Medicine or at least something that has the same classes.
http://www.goarmy.com/amedd/
Graduate with good grades. NOW call an Army AMEDD recruiter. They can help you with your existing loans, and get your tuition paid for or mostly paid for for medical school. You could go Reserves at this point, or wait until you are done with school. You could even go to the military's free medical school:
http://www.usuhs.mil/
You won't hit the Army until you graduate, and you do your residency through the Army's hospitals. You would come into the Army as an officer.
If you have no resources for college right now, you could enlist as a combat medic and then use the GI Bill for college and medical school. It would slow you down by three or four years, but you'll have some life experience and some money saved up, if you are smart about deployment money.