Sick kitty for a week now....anyone seen anything like this?

I have a fixed male cat part Maine Coon about 21 months old, he is up to date on all shots, etc, is an indoor cat so I dont have him on heartworm or flea treatment (per vet) and he has a full sister who is healthy. 

Last week on Thursday night I noticed he was not hanging around and realized I had not seen him much that day. I found him hiding and he felt really hot (could not take temp as my thermometer was dead) so I waited until Friday and took him to the vet. He had a temp of 105.8, they kept him and did all sorts of blood work and xrays all which came back normal, no kidney, liver issues, not leukemia or aids, no masses or blockages in gut, chest areas. So they gave him iv fluids antibiotitics and anti inflammatory injections and finally on Sat his temp was normal so I took him home with instructions to give subq fluids once a day. 

some of his symptoms besides lethargy, not eating or drinking and fever are neurological, he seems weak on his backend and cant jump, he swallows hard like something is sore. 

He went back to the vet Monday and I got a couple meds (same as above) to give him daily and he is seeming to be getting better daily (no fever since monday morning) with a better attitude and not sleeping as much. However he will still not eat or drink. The vet had me stop the subq fluids monday to see if he would drink. I have tried everything I can think of food wise to get him to eat and I did get him to eat a couple temptation treats and a tiny amount of tuna (more the broth than the meat) and some broth type treat I found at the store, but not much of any of those things, I have tired at least 6 different kinds of food, lactose free milk and still not much going into him and still no water. The vet is not too worried right now about organ failure but I will be taking him back tomorrow (friday) if he does not drink today. I have been sleeping in the living room with him on a recliner so that I can hear his every move to see if he gets anything at night but so far I have not caught him doing anything and since I have 2 cats its hard to say who is eating and drinking unless you catch them. I will be trying to separate them tonight to see if he is doing anything the hour or 2 I am actually sleeping. I am really stressed and just want to know what is wrong, Anyone here ever been through something like this, should I be worried since his attitude is getting better? I need sleep

ask for antinausea meds. Cerenia or Zofran. whatever was going on is making the stomach upset. licking the juice and walking away is one sign its nausea. lip smacking. sniffing food and walking away. ask them about antiacid pills-Pepcid=plain Pepcid. they can give you the dose instructions. its bitter tasting so don't crush in food. you can also get Cerenia and Pepcid as injections if pilling is not possible.

have him checked for heart problems. Vets don't check them that young, but him being part Main Coon, it could be an issue.

Very sorry to hear about this - hang in there.

thanks for the suggestions, that is one thing I didnt think of. I will ask the vet about that tomorrow. 

A friend said something about heart issues but being so young we both thought it was not possible but I will ask my vet about it. thanks for the suggestion. 

An update on Turk, he is still not eating or drinking very much if at all. I asked about the heart issues and meds for nausea but the vet does not feel its his heart but we will check it if the fever and weak end comes back, and for the nausea meds the vet said since he is not throwing up, he does not want to give anything for that yet as the xrays looked so good, I spoke to him yesterday. This morning Turk is acting much more himself, grooming, watching things, playing with his sister a little so he is almost back to normal with his attitude but still not interested in food or water for the most part. I have been giving him Metacam and Orbax orally since Monday once a day and after I have him his dose today I got to thinking what are the side affects of these meds.....well looking at them both, decreased appetite and digestive issues were on them. So I will be calling me vet to see if I should stop these meds to see if he will start eating and drinking. He was on the meds because of the high fever and they were not sure what was wrong so they were giving these meds as they brought the fever down and since he has not had a fever is a few days I want to stop the meds to see if he eats and drinks, I just hope his fever does not come back.