I had the same thing happen to me when my first baby had his first vacc's done. I wouldn't be inclined to give him more unless you are absolutely sure that he brought the entire dose up, otherwise you run the risk of overdosing him accidentally kwim? Is he still awake ATM? you could try popping him in a nice deep, warm bath as his little legs would be feeling a bit sore, plus the bath will help bring his temp down if he has one. Sometimes all we can do is comfort them.