Turning 19 and losing all coverage, what can I do?

I just received a letter from my state's social security office stating that under my parents plan (grandmother took custody of me due to family issues) and I called them and they stated that I would lose all coverage when I turn 19, and the state doesn't offer any other type of insurance for me. I was wondering what I could do in order to battle the issue as I am still a student going to college and I have major appointments with my doctors coming up after I turn 19 as well. Any information would be appreciated.