I can’t afford it. I didn’t pay to have him put up there. My sister did. Do you know any people here who might be able to help?

I think you’re better off asking some pet care blogs, or looking up how to help an abused and timid dog. In the meantime, don’t make him wear his collar. Maybe see if you can get one of those chest harnesses, try to get him used to that instead. 

Basically, go look for an expert. Maybe call a vet (phone calls to vets are free) and see if they have any advice or can point you somewhere.