I had a female husky for 16 years and she was a self feeder and would go 2-3 days before eating a full bowl. We now have a black lab who is hypothyroid. Prior to being diagnosed, she was sleeping constantly and her hair was thinning drastically and nearly bald on her hind quarters. She could barely walk any distance because of fatigue. She had what the vet called “thyroid fog” where there was no spark in her eye and no emotion. Her thyroid function level was so low when they tested it that it didn’t even register. Much of what is going on with Diesel sounds like a dosage problem with his thyroid medication. Was there a reason why his dosage was changed so dramatically? I’m assuming the vet was doing blood draws to check to see if he had reached a therapeutic range. If they were not checking his levels it’s likely that his dosage is incorrect. Our Zoey is on 1 mg of thyroxine 2x daily and it is the maximum dosage for K9. Diesel probably has bare spots due to the hypothyroidism because once our dog started the medication all her symptoms quickly subsided and her hair began to grow. We struggle with Zoey’s weight even on a 4 Cup a day diet. Labs love their food and she is Miss Piggy. If it’s not his thyroid I would be concerned about his adrenal gland. Hope you can get him back on track with your new vet! Best of luck!