Thanks everyone for their posts!
Tobi has gotten a lot better in the last day. I made sure he had enough water, but I did take his food away from him. I'm taking him to see another vet until tomorrow (one that has been recommended as reliable). He hasn't shown any signs of pancreatis since then, and is just his normal self....rowdy and playful. I opted to wait a bit so that I could see this particular vet, as the vets in my town are notorious for overcharging.
Thanks again everyone!
PS: nope, didn't pay the $1200 for the neuter....got everything done for $80
and yup, he's had his worming shots 4 times now