My puppy Coco just had the same thing happen to her today. Yesterday she got her last set of puppy shots and then today I could not get her to eat and she had diarrhea. I just got back from the vet and they gave me some antibiotics and prescription diet food but they thought it was a reaction to the injections...but it cost me $100 at the vet!!!
Ohh well, at least I know she is safe.
I hope your fur-kid is okay.
Take Care,
Aly
Coco's Mommy