No, rescues are not in the business of funding the dogs care after placement. I will be happy to forward this on to Donna for you though.
Two things stand out here. First, I firmly believe that there comes a point where things are over complicated. I think you are there. Were this my dog, I would put him on a RAW diet (no grains, no starch, no kibble, nothing) and remove all but the thyroid meds to give his body a chance to heal. No more steroids, no more allergy shots, no more anything. I think between the drugs and the strange foods, he is not being given the opportunity to heal.
The other thing is that sometimes the dogs truly are allergic to their surroundings. We got a dog in our rescue that the owners flew up from Florida. The dog was allergic to that Florida grass and there wasn't a thing they could do about it. Keeping the dog doped up for his whole life was not the right thing, so she sent him north, away from the environment.