Lee Anne - I sure hope Angel is recovering quickly!
What your vet wants to do is the best thing. My little Stormy is so tiny that the vet will not give her more than one shot at a time. Her first shot she was barely a pound and the vet gave her a shot of Diphenhydramine 20 minutes prior to her shot to minimize the chance of any reaction. Worked like a charm. Now that she's a little bigger she does fine without the Diphenhydramine, but we always wait at least 20-30 minutes afterwards at the vet to make sure there is no reaction.
There are shots that are combo shots and shots that are single shots - all depends on what the vet uses. Stormy had a combo shot through the breeders vet - I think it's called Univac-5 - and just single shots since from our vet.