My husband has severe pain on the side of his foot where he can't walk. Unfortunately, he has no health insurance. I tried applying hot (heated in the microwave first) wash clothes and did not help at all. He can't even walk without being in severe pain.

He needs to have an X ray at the least, for possible fracture. Even a hairline crack of a foot bone can be extremely painful. So the question is how to do it for the least cost? Call around for walk in clinics, anything to avoid the ER cost. Many hospitals have associate clinics nearby.
You should find out anyway, for any future emergencies.