Note - this is in the USA.
You are worried about a medical situation ruining you financially, we know that you live in the USA, but the rules in the sidebar want you to edit the title to say [USA].
One of the major problems with collections, is that there aren't any checks and balances. Whoever can just get a collection agency to go after basically anyone. Once it gets to collections, it's often on you to try to prove that you don't need to pay the bill, and not them needing to prove that you do need to pay the bill.
Does your medical insurance advocate on your behalf, can you send them the bill yourself for them to deal with?