My highland lynx of 8 weeks has diareah can i force him to eat only dry kitten food instead of mixed can and d?

my kitten eats dry food mixed with wet kitten food from iam's he still has a wet stool what should i do been this way sice i brought him home he was on meds for herpes but now has finished this yesterday. can i give him just dry food or should i change his food to something else or should i have him dewormed again..plzzz help he is very active sleeps well eats well.he eats wet food and dry mixed together right now.and is still sneezing i give him the vitamins in the pump form for this .