my kitty got sick

My cat of 7 years was healthy and for 2 days he was just laying on the floor and in closet. Took him to vet and they said he had bladder crystals and he need to be in hospital on iv s and catheter for 3 days . then said he can go home in 2 days got him home still was the same took him back 3 days later and said sometimes it take time to heal .So took him back again when the vet got back and said he not eating or drinking they took him out of room . And came back and told me we did a blood test your cat has leukemia and aid . I was in shock can a cat get that all of a sudden never had any signs of being sick . And a week later he was gone . They said there was no cure but that fast no iam wondering if they misdiagnosis him.

And charged me 850.00 . Missing him so much

I'm so sorry you lost your little guy.  It's just heartbreaking when they die so suddenly like this and you've had no idea they were ill.

Did you have him vaccinaated when he was young?  Usually these type of diseases are vacccinated against when they are babies, and also tested for when they are small, usually before they are adopted out.  They normally take time to "kill" a cat, sometimes years, and the cat should show signs of illness for quite some time before they die. 

That being said, if you see the blood tests your Vet ran, you should be able to see the results of the tests and see if they show positive for FeLv and FIV

http://www.thecatsite.com/a/fiv-in-cats

http://www.thecatsite.com/a/feline-leukemia-virus-felv

I am terribly sorry for your loss. Cats can carry both FeLV and FIV for many years without symptoms and then develop a disease. That said, it's strange that the vet mentioned both of these horrible diseases at once. I wonder if maybe they found that the cat was positive for both viruses? That does not necessarily mean it was the cause of death.