MMRV Vaccine

My 18mo just had the MMRV vaccine in the morning, but at abt 5pm he starts vomiting whatever he eats/drinks until now (9.38pm). I was told by the nurse there was a probability of fever in a few days but i didn't expect vomiting. Is this normal or should i rush him the hospital? P.S: He is fully breastfed and he eats what we eat, so i doubt its food poisoning.