Ds3 just went through this a couple of months ago, I thought he'd gotten chicken pox too but was just a reaction to the needles (he had alot of spots) all happened within a week or two of his vaccinations.
They didn't scab or anything just disappeared within a day or two of them showing up.
I took him too the chemist and doctors who confirms it was a reaction.
My other two boys never got a reaction to any needle so I was certainly was concerned.
Supposedly a rash can appear after about a month of having the vaccine I read on the print out the chemist gave me to look through.