Wanted to post this in case others have experienced a similar thing. About 8hours after my DD had her MMR vaccine, she vomited. And then again. And again. It was about 10 times in total in a 12hour period. Then she was fine until 2 weeks later, when she had mumps-type symptoms - really swollen glands and a temperature and very tired. She had only ever been sick once before in her life and no-one else in the house (5 of us) was ill so I do think it was a reaction to the vaccine.
I think it's important that people know that the reaction to MMR can be horrible, although obviously nowhere near what any of these diseases would be.