Thanks guys. This happened last year as well. He spent a week at the vet and they were never able to pinpoint what he had--which makes what may be a repeat performance all that more frustrating. He at least doesn't seem nearly as sick as last time. He was practically catonic then and was having diarrhea and vomiting. This time, he's been eating and drinking pretty normally and without incident. It's really the fever primarily. I kept him at the vet so that they can keep a close eye on him. If he doesn't respond to treatment in 24 hours then we'll start running various labs. He had bloodwork in late July that was normal. Ugh.