Weird symptoms--help!

About a week ago my cat seemed physically injured. I picked him up, and he screamed like he was hurt. I put him down and searched for any visible injuries on his body, and couldn't find any. He didn't move much that day, but the next day he seemed 100% back to normal. About 3 days ago, he started acting like he was sick. He wouldn't move from the spot on my bed, he was sneezing, he wouldn't eat, he wouldn't drink. Something was definitely off as he wouldn't even eat tuna when I stuck it under his nose, which he usually goes insane for. Yesterday morning I put water under his nose and he drank quite a bit, but still wouldn't eat. I took him to the vet that day, and they couldn't find anything wrong with him. He didn't have a fever, he didn't seem dehydrated, the tests for feline leukemia and others were all negative. They gave me some antibiotics to give him just in case and sent me home. Today, he's acting waaaay out of character. He started walking around the house more, but as far as I know still hasn't eaten anything and won't drink anymore. He's acting like he doesn't know what anything is. Like he's seeing things for the first time. He almost seems like he's hallucinating. He stared at a rug, while constantly moving his head in a circle like pattern, looking like he was going to fall over, for a solid five minutes. He then did that to a basket, the laundry drier, and other various things. I've never seen ANY cat act like this, much less him. It's unsettling to watch, and I have NO idea what's wrong with him. Still won't eat. I'm calling the vet again tomorrow. Any ideas?

Could he have gotten into anything that is toxic?

I suppose it's possible, but there's not anything off of the top of my head that I can think of. We don't use pesticides or anything like that. He is an indoor/outdoor cat, so it's entirely possible that he got some sort of toxic plant or something. But everything I read about toxicity states vomiting/diarrhea as a symptom, and he hasn't done either of those. I'll definitely ask the vet tomorrow about the possibility though! Thanks for the reply.

How does his coordination seem? Does he seem to have any balance/jumping issues? I would almost be suspecting neurological at this point, but I'm no expert by any means. The circling of the head had me wondering. Perhaps inner ear infection? I know with my rats at least, when they start seeming uncoordinated and spacey, we strongly suspect pituitary tumors - though I've no idea how common those are in cats.

My apologies if you mentioned it, but how old is your kitty? Any health issues in the past that may pertain?

I would have suspected and inner ear infection, but his coordination seems fine (for the most part). While he was staring at things, his coordination seemed off, like he was about to fall over at any moment, but then he'd walk around and jump up on furniture and it seemed fine. Yeah, the head circling has definitely been the most unsettling part. And I'm sorry, I should have mentioned in my original post that he's very young, only two years old! He hasn't had any health issues so far. I was suspecting something neurological too, but he's just so young. Maybe a head injury?

I know you said he had a FeLV (feline leukemia virus) test done and that came back negative. What others came back negative? Did they do a full CBC? How about x-rays? How long has it been since he had a full meal? If, from what I read of your original post, he hasn't eaten in three days, then his liver is at risk. This is critical. Cats can go into hepatic lipidosis (fatty liver disease) in as little as a few days if they are not getting their normal daily caloric intake. If he's still not eating, you may need to begin assist-feeding him.

I tried typing in head circling and not eating on google, just to see what came up. One that might fit the symptoms was:

Hepatic encephalopathy: is a neurologic syndrome seen in a number of liver diseases. Signs suggestive of hepatic encephalopathy include circling, head pressing, aimless wandering, weakness, poor coordination, blindness, excessive drooling, aggression, dementia, seizures, and coma.

Taken from this link:
http://www.merckmanuals.com/petheal...ers_of_the_liver_and_gallbladder_in_cats.html

Another interesting one that I saw was Nystagmus:

http://www.petmd.com/cat/conditions/neurological/c_ct_nystagmus

& Vestibular disease:

http://www.vcahospitals.com/main/pe.../animal-health/feline-vestibular-disease/6509

Again, I really have absolutely no clue on this one but I'm just throwing things out there that might fit the bill. I'd definitely be interested in bloodwork, a good ear check, possibly a urine test if they can get anything out of him.