most doctors who specialize won't see you if you're under 18, and you have to be really sick to get a medical card under 18. I mean, I've never heard of it happening and doubt it's happened more than twice.

Don't rape the system man. If you're not sick don't do it, you're just making it harder for people with legitimate illnesses. If you're under 18, you're in no real trouble with the law. Unless they're trying you as an adult, then I'd change your name and move to a different country.