I have a friend that says her cat has allergic reactions to the shots, but she feels it important to get all the shots, even if they don't go outside. If you walk in and out your self you can track in The soils that has dangerous virus's & diseases from outside.

I have never had that problem with my cats so I can't give you any suggestions about your kitties reaction to the vet. Maybe like
Kirsten says:
maybe he reacted like that 'cause the vet visit has been too exciting for him - or he has just upset his stomach.

I hope you good luck with your kitties! They do have cute names!