http://www.huffingtonpost.com/jason-alderman/what-happens-when-you-can_1_b_1702356.html
You mentioned your credit score taking a hit because of medical bills. Don’t just ignore medical bills (or any bills). Contact them and see if some of it can be forgiven for low income households or you can make small payments on the bill if you don’t have insurance.
The offer sounds pretty great, with just a few thousand missing. Would you be willing to do work/study or work this summer to make the necessary money. It would be a shame to turn down this offer … and I think they really will work with you to help you figure out how to attend. You can have your mom apply for the PLUS loans … she may or may not qualify, but use that money at most for those few thousand, $5K total and pay them off first …
If commuting is easily doable, without spending hours a day in your car, that is also a good approach. But you need to discuss this with financial aid, as it may reduce your award … or … may not.