It all kind of depends. As others have said, try Medicaid, HRSA, state or county human service organizations, or go to public health clinics, if there are any in your area.
If you go to a dr in a large practice, you probably have to deal with a billing person, however, you should still discuss it with your dr. If it’s a sole practitioner, you have to talk to the dr. They will often be sympathetic and offer care at no cost or a reduced cost. It can’t hurt to ask. Don’t be ashamed to ask.
If worst comes to worst, go to an emergency room. They have to treat you. You’ll be a “self-pay” patient. They know that many people can’t afford to pay (and ERs cost a lot more). If you can’t pay, you can negotiate with them for reduced costs. At least ask. In the end, if you can’t pay, it will hurt your credit rating, but frankly, your health is much more important that your credit rating.
Go get care! Don’t wait. I don’t care if it turns out to be nothing. Your health is more important than anything else. Without it, you can’t live or your quality of life could be severely diminished. And frankly, politically speaking, the more patients who can’t pay, the more physicians will start screaming for a real universal health insurance program. They don’t like insurers any more than we do.