Thanks, half an hour later and he's perking up a bit, wanting to play. I'm mostly just ignoring him to avoid encouraging it while keeping an eye on him.
I was told not to offer food until breakfast tomorrow, and then only a small amount at first. I feel kind of bad about it, but I also don't want him throwing up. I'm hoping he settles down when I go to take my nap (long day, up early to drop him off, then off to get two teeth pulled for me
so we can all get some rest.
I'll move his litter box into the bedroom and shut the door when it's bedtime, though, that's a good idea.