No it's probably just a normal reaction to a shot. Keep doing what you're doing. (I'm sure you are, but make sure you're using generic tylenol/motrin due to recent recall!) You could probably wash him off in a cool bath or with a cool cloth too. If you're worried I bet your town has a 24 hour nurse call line like ask-a-nurse or something, but really, I think it's just a standard reaction. Good luck and I hope he feels better soon!