What Causes Vomiting In A Child?

hi my baby is on formula (cerelac 4 , with flavor of rice ,patato,chicken) though she is 32months ..recently i follow when her mom give her cerelac in the morning then after two hours give egg after then she did vomiting ... i dont know what is the reason behind that... her mom and me really concern about it... in fact this is happen sometimes not frequently.. so would you pls tell me can i continue cerelac or not? how can we resolve the vomiting problem? pls let me know then i really grateful to u...