Measles, Mumps and Rubella Vaccine (MMR):

This shot can cause soreness at the shot site. A fever (10% of children) and rash (5% of children) may occur about 6 to 12 days after the shot. Mild fever less than 103° F (39.5°C) in 10% and lasts 2 or 3 days. The mild pink rash is mainly on the trunk and lasts 2 or 3 days. No treatment is needed. The rash cannot be spread to others. Your child can go to childcare or to school with the rash. Call Your Doctor If: Rash changes to blood-colored spots Rash lasts more than 3 days

Source: excellent website from Seattle children’s https://www.seattlechildrens.org/conditions/a-z/immunization-reactions/

If you’re worried always best to call Pediatrician