I do see what you mean about him getting thinner. The backbone is showing. How old is he? I'm wondering if he should have been huskier to handle being breed to a female. when you intend to breed you need to pack on the weight as much as possible.

Do you know if hes been drinking to get his fluids?

Hmmm....I have to stick with raise the temps in his enclosure, feed him in his enclosure, and just keep trying. I believe you said its been about a month right? I think its still a little early to be overly concerned. I would just try to make the few mods and see if it pans out.