Chins weight loss/diet

Good morning. Need a little help if possible and forgive the long post as we have been dealing with a situation since late December, early January. So we noticed our little guy was starting to drop weight. He was always in the 520 range and my daughter (it's her chin) was noticing he was feeling a little lighter so we started weighing him daily to keep track. It started with we noticed he would leave little urine puddles here and there while out playing and then she noticed little red marks on his fleece in the cage. She figured it may be a uti so we took him to the vet right away. They didn't test his urine but put him on baytril "just in case". After 2 days on Baytril, he pretty much stopped eating and his poo was less and less and really hard. We rushed him back to the vet and they did an xray to make sure there was no blockage. There was not so they told us to quit the baytril. Well his weight kept dropping fast so of course, call the vet. We ended up being referred to a more chin knowledgeable vet. Got him in right away and he did a mouth xray (so we thought) and saw a sharp tooth that was rubbing against his tongue. He filed it down and we thought all was good. Well the weight kept falling and so they took him in overnight to monitor him and found nothing. We were beyond frustrated and was able to find a highly recommended exotic vet about an hour away from us. They luckily got him in fast. They did every test available. Xray, blood test, teeth check. His teeth are perfectly fine. No malo, xrays were good. Blood test came back with his blood cell count being really really low. They sent us home with Baytril (a strong but easier dose for him than the first) and a second med which I can't remember the name. We were to do the second med for 5 days 1 time a day and the baytril for 7 days 2 times a day. We went back about 12 days later and his red blood cell count more than doubled which is great, but still not where it needed to be. They are seeing if his blood cells recoop on their own without meds and we go back this Friday to have another blood test done to see hows hes done.

Since the last visit he has started eating more on his own and not taking the cc or essentials for life as much as he was before. While he was on the meds, he would easily eat 50-60 ml of essentials for life. He started not eating it as willingly but we noticed he was drinking out of his bottle again and eating pellets/hay more. And he was starting to gain a little weight at a time on his own. His lowest weight was 417 while on the second round of baytril. Since then, he has climbed up and was able to get him in the 450's while hand feeding him. Once he started eating on his own, he had been maintaining the 445 range. A couple of days ago though, he dropped down to 430 and is back to not eating as much. I'm really praying that his blood cell count hasn't dropped back down. Has anyone had this similar situation?