I'm supposed to watch his poops religiously over the next two days, and make sure he doesn't throw up at all. I also have some medications for him. An antibiotic and more laxatives to keep him pooping.
When he came home, he was pretty skittish, but he's bounced back pretty quickly. He didn't really want to be held or pet right away. He just made a beeline to the litter box :P He was very thirsty and sat in front of the tap in the bathroom until I turned the sink on for him. I guess he didn't like the kind of water dispenser they had there, or was too scared to drink much. He's always been the kind of cat that drinks a ton of water.
I'm still really worried about him, but at least he's home now.