Ozark,
Did they test him for Leuk and FIV?
Yes, that was the first thing they did. Test him for those and since I got him at a shelter, I think we were both convinced that would be the problem. They both came back negative so they did a blood test, his temp was high (105 normal cat about 101) and his white blood cell count was very high but according to vet not alarming. He's on antibiotics now and way better. Back to his normal self but it took a couple days and I had him scheduled for another visit because 48 hours later, he was still terribly sick.