Hospitals often have programs where they will waive all hospital costs if you qualify financially (that wouldn't include doctors, etc.) It's worth a call to your local hospital to see if they have such a program, & if it would cover the type of work you need done. As Rose suggested, Medicaid would cover much, if not all, of the cost of doctors & testing, but calling the hospital to find out how they might help is worth a shot, too. Rose probably expressed things better than I did.
It sounds like your condition is very serious. I'm sorry you find yourself in this situation. I wish you luck.