(Jason) wrote:

What I know so far is:
His temerature is normal

Usually a fever indicates an infection, but you can have a sick cat that
doesn't have an infection or fever.

He will not eat, or is eating VERY little
He does not appear to be drinking
His blood tests, xrays, and urine tests are all OK

This sounds a bit like my cat when she had a mild case of pancreatitis. She did
not have a fever. The only test that indicated anything abnormal was a test
that took several weeks to obtain results, and by that time she had long been
back to normal. The test was specific for pancreatitis.

He appeared healthier today but still has diarrhoea
He was not vomiting in the hospital
His vomit was originally white and foamy

That means the cat is nauseated but there is nothing in the stomach to vomit.

This progressed to green after a couple of days

That means the cat is vomiting bile. Again, it means there's nothing in the
stomach to vomit.
He tends to vomit right after a bowel movement
He was having some inadvertant bowel movement during vomiting earlier
on

The vet seems to be stumped, and I cannot afford an infinite amount of
tests. Has anyone elses cat suffered through this and what was the
cause???

Unfortunately, these symptoms are so vague as to indicate any number of things,
many not terribly serious. With my cat, the vet prescribed an appetite
stimulant and antibiotics. We only needed one appetite stimulant to get her
started eating again. After that she began to eat normally, but she wasn't all
that sick in the first place. Your cat could just have a case of gastritis, but
the important thing is to get him eating again soon.