You're in the Dentist's chair, you just learned that you need a Root Canal, and you have no Dental Insurance.
To quote the late Karl Malden: "What Will You Do????? WHAT WILL YOU DO????"
One solution being used more and more is...
If your only income is Social Security or SSD, you can file bankruptcy. But you may not have to.
If you do not plan on going back to work, you may not need to file bankruptcy because you are considered to be "judgment proof". That means that while your creditors can sue you and obtain a judgment, they may not be able to collect anything from you.
Creditors generally cannot recoup any money from your social security income. You should determine, however, if you own any other real or personal property that creditors could get their hands on. It is best to review your situation with an experienced consumer bankruptcy attorney.
There are a number of sites on the internet (which I shall not link to in the interest of public education) which are completely wrong in stating that medical debt collection does not affect your credit score.
Medical debt which has gone to collection is a debt which has gone to a debt collector and is scored the same way (and looked at the same way) by potential creditors.
Scoring is what potential creditors look at -- the most common one is the FICO score.