My Cat is sick! colitis?

Question
My cat has been laying down for the past 2 days and isnt acting like himself, he's been sleeping lots and seems to be in pain. I think it may be colitis but i'm not sure, i'll give you all the details i can.
-has been making a heaving or hiccuping motion but has not made noises from it.
-he has started walking funny differently, slowly and not very much.
-when he sits down, little watery puddle with a bit of watery blood is left behind.
-he is gassy
-he will only walk for a minute, usually to a different room to lick himself, then comes back and lays down again.
-he is constantly licking his bum.
-he is around 6 years old.
-he is an indoor cat and the only pet.
-there have been no recent changes to his diet.
-he threw up once and it looked like undigested food.
-he cant stay laying in one position too long.
-I havn't seen him eat or drink in 2 days and he is very depressed looking. He wont stay near us and when we go to see if he's ok, he gets up and walks in another room almost as if he were embarrased or ashamed.
-he is an overweight cat but usually doesnt act ike this, he is usually very active and loving and doesnt usually eat anything unusual like hair elastics or anything.
-the only new thing i can think of is that now that my brother doesnt have his dog anymore, the cat has been sleeping in the dogs cage. the dog was an outside dog, but was never really around other dogs, and he was healthy.

if you could please help. I'm making my cat a vet appt. but i live in a small town and around here, if people think their animal is going to cost too much at the vet, the owner usually just "gets rid" of the animal. I dont want this to happen to my brothers cat but i just moved here and dont have a job yet so money is tight. is there anything i can ask my vet to focus on so maybe unnecessary tests dont need to be paid for? does this seem like a sudden case of colitis?

thanks!

Answer
Liisa,

Remember, I am not a vet, but stomach problems are often difficult to diagnose, and there are many, many different things that could cause the behaviors you have mentioned. So, the tests I would ask for are a complete blood panel.  I would take a stool sample in so the vet can test it for intestinal parasites.  Cats are very stoical about pain, so his behavior would indicate that he is in some discomfort and just wants to be left alone.

So, once you get to the vet with stool sample in hand, make sure you give the vet as complete a history as you can and, hopefully, you will get to the cause and a reasonable treatment for what ails your kitty. I would not mention colitis, but let the vet figure out what is going on.

Please let me know what you find.

Best regards... Norm.