The Doctor should have given you an information sheet, on the MMR vaccination. Or for any vaccination. At least that is what our Ped does.
So read that... and it will list the possible side-effects or after-effects of the vaccination.
IF your child was under the radar sick, when she got the shot (but they should have taken her temperature before giving any shot), then sometimes this reaction to the vaccine may be coincidental. After effects from a vaccine, can sometimes indeed occur up to a week or 2 after the shot was given.
Call the Doctor, and ask them again, since you are concerned.
Also, she is probably 'cranky' because she has not been sleeping well. She is sleep deprived. At this age, they do still need naps... but I understand since the shot, she has not been sleeping well.
My kids, when having had their shots, usually do sleep well after.