prescription and regular dry?

my two cats seem to have very sensitive tummies and they're on nutro natural choice dry, it works but not consistent especially on my 5 month old, my question, you think it will work if i mix prescription dry I/D and the nutro? my 5 month only eats dry.

Talk to the vet... Kittens can be sensitive to alot... If possible bring a stool sample to the dr.. rx food is great but not if it aint needed

they had been checked and cleared of parasites, yeah, i should consult my vet.