Taz seems to be getting back to normal. He is eating and drinking now, and he's becoming more vocal (he's my alarm clock when the sun comes up). He isn't back to playing yet, but I haven't noticed anymore vomiting since Wednesday. I also haven't noticed him getting in and out of the cat box, but he may be doing that when I'm not around. With three cats, it's hard to tell which one is doing what. I'm keeping a watchful eye on his personality, because that's always the first thing that gives how they're feeling away.