Earnest gets sick from shots, he runs a low fever, gets diarrhea, and lays around for about 24 hours. I NEVER do all of his shots together anymore, and if the vet doesn't like all the multiple visits then I switch vets. Rabies and Leptospirosis are the ones most likely to make them sick, I do each component in the DHLLP- also known as 5 way-(distemper,hepatitis,lepto,parvo, and I forget what the second P is for) at least 10 days apart. It's a pain to keep going back in, but definitely worth it, he hasn't had a really bad reaction since I started spacing them out, although he still gets pretty droopy. More and more vaccines are getting approved as 3 and 5 year too, I know yours is just a pup, but next year when he needs his adult boosters, find a vet that uses multiple year vaccines, so he doesn't have to have them so often.