The weirdest virus I've ever seen

You know how we had to come back from ATL early because Jayce got sick? Well, he's still sick.
But not really.
Well, only sometimes.
I guess you could say that he's fine during the day, but then every night the past 5 days, he's ran a fever (as far as I can tell by touch) and thrown up. Then he goes to sleep. Wakes up at 4:30 in the morning crying. Goes back to sleep until 8 AM.

Tonight he didn't look well sitting up in the computer room with all of us, so I carried him downstairs so he could cool off a bit. I laid him on the couch while I started fixing Jaina dinner. Brian walked in from picking up Applebee's for us and said, "What is Jayce doing asleep at 6:30 PM?"

I hadn't even noticed! I thought he was watching Brother Bear on TV. So I picked him up and carried him to his room, not bothering to change his diaper or try to get food into him. That's when I stepped in something wet on the floor in front of the couch. I came back to investigate and found a huge wet spot where Jayce had been sitting. Since he hadn't eaten anything since before lunch time, it was really easy to clean up, but still... why is he throwing up nightly?