I called the vet this morning. She had good (ish) news! He did not throw up over night, and apparently he's quite a bit happier. He's perkier and is now pretty yappy so that's really good to hear. I guess the anti-nausea medicine is working!
She did say he still wasn't eating, and she thinks it might be because of the food they're trying to feed him. Because of the damage to the intestinal tract, they have to feed him something that's easy to digest but in turn is quite bland. (I believe it's the Science Diet Prescription line... is that any good? I know I'll have to follow the vet's feeding instructions and they're planning on sending us home with 10 days worth but I've just heard some not-so-great things about SD. Is the prescription stuff different?) If he still refuses to eat that, she's going to try feeding him some regular puppy food. Turns out he's a picky eater

. That's mommy's boy.
Anyway.... the vet said she'd like to keep him til at least tomorrow morning for observation but if he can keep the food down.. we might get to bring him home within the next couple of days!