Cat not being normal self, PLEASE help

Today my almost 6 month old kitten started acting really weird. He refuses to touch our bedroom floor (he will touch the living room floor), he is acting very very spooked of everything like a baby kitten, he feels slightly shaky, and has no interest in any type of distraction. He just sits on our bed or table barley moving and just sniffing and watching the floor. I was playing with him like normal very excited and very playful but ten minutes later everything changed. He hasn't started acting normal for so far 5-6 hours now. Ive tried to get him to eat and drink water but he just smells it and sits down. We have had him since he was six weeks old and he has never acted like this. Also he did vomit once yesterday but he never stopped being himself. I just was hoping to get other inputs, thank you all for your help. The vet opens in 4 more hours...

My cat (11 months now) stops eating for some 10-12 hours after vomiting or after a not normal pooh. Then resume eating and drinking. My vet suspected a contaminated food (some lots may get contaminated or the guardian (owner) may forget to remove the wet food after to amny hours in the bowl - staff like this).

However, I got the habit to closely look to the cat whenever things like this happens. 

My check list:

- paws injuries (once the cut was so small that only the vet using a magnifying glass could spot it): the pink "pillows" and the area between them

- ears (black matter, injuries)

- belly (abnormaly hard or to skinny)

- eyes - tears, blinking

- mouth  - injuries, small toys or leftovers 

- body pose  check - comparing to the usual one 

===

Sometimes my cat just "visit" the food or water bowls, from internet and forum post i found this behavior as rather spread (my personal opinion is that the cat just make sure I do not eat his food :-)).

===

Refusing to touch the floor may be from chemical reasons or for strange shadows on the floor from some object at the window/ in front of the lamp. Chasing shadows or being afraid of appears to be a rather spread behavior of kitten. 

Thank you so much for your response, I completed the checklist and it seems only his stomach feels hard. He did eat normally this morning, but I was looking for something with a flashlight and since then he was acting like this. He just seems like everything he once knew he has to make sure everything is safe or something won't come out a get him. He just ate some food out of my hand but still no water. I haven't used any chemicals on the floor and ten minutes before he was acting like this, he was running, playing, jumping. Then it all came to a complete stop, he just seems like he has so much fear in him that he seemed to have never had.  His body pose is very nervous like, he has his tail low curled up next to him the whole time sitting or walking, and takes slow unsure steps. Again thank you so so much for your reply.

It does sound like he doesn't feel well. Can you take him to the vet? Is he neutered?

I was told (but I cant document this opinion) that cat do have a memory pattern that is similar to humans. So, they may remember some events (again, I have no proof, just rumors and anecdotics). If a not pleasant event , then the cat may link it to something in his surroundings (similar to refusing to pee on the litterbox when pee causes pain).

Body pose significance: you may search the net for details. In brief, if the ears point backwards = the cat is afraid (among other feelings).

Cats "talk" using ears pose, tail pose, body, whiskers. They are very talkative in this sense (at least some individuals). Some poses serve to communicate a need (drink, food, affection) or a request for a certain behavior  ("leave me alone!"). Some are to show relaxation, confidence  (exposing belly) of pain (more discrete, difficult to describe).