My 9 � month son is sick. Doctor said to use Benadryl?

You should be giving him benadryl for infants. Until he is over 1yr of age he should not take any children's medicine, plus the infant version is sweeter so he will take it better. Good luck, it is very frustrating to see your little one suffering. If he does not get better in a week I would def call your pediatrician agian and update her.