I'm not sure I remember your Cocoa, sorry. If he is a pure breed, maybe breed rescue can assist you.

Is there an SPCA in your area? Or an Animal Rescue League?

I know you said there are 3 vets in your area. What about traveling a bit further, just to help the dog? Start by calling, no need to be driving all over the place.

Is Care Credit an option? Can you find a vet that accepts their payment plans?

Just trying to generate some ideas here. Prayers for you and Cocoa!