The almost exact same thing happened to me. The first time I went in, I was rushed out on Christmas Eve morning. Not to sound discouraging, but I ended back up in the same treatment center a few days after my release, and then again a third time after that.
The black stuff is liquid charcoal. It's supposed to make you throw up to clean your system (more or less).
Honestly, I'm not even going to suggest family, friends, teachers, etc. for support. They may or may not be there (I'm not going to assume anything about how good your relationships are with your mother and father), but if they ARE there, they might be able to help you. Even if she's in a different state, there may be a way to at least contact her. But, really, the way I looked at MY treatment, it was all on me in the end. I have to look inward each day to discover new things about myself to give myself. It doesn't work a lot, but at least I give it hell each and every day.
As far as insurance goes- treatment is the furthest thing from free. So not only would looking for ways around going back to the hospital work better- it would also be a good financial decision. And I know that most people will tell you that if you need it, money shouldn't matter, but, hell, if everyone thought like that no one, and I mean NO ONE, would have a penny.
And, I guess I SHOULD suggest this... call someone. Especially if you don't feel safe, try it. Didn't work for me, but you may have better luck with it.
Stay calm, stay strong, and the rest should fall in to place if you just keep trying.