aww buster dont go worrying yourself if buster was fine last night then it just may be an upset stomach he could of eat something that didnt agree with him if hes got a sensitive belly then im sure that this is the case,if he hasnt been sick since and hasnt had any more diahria then he will be fine hes going to the vet friday to be boosted so he should be alright if your still not happy you can always phone your vets and explain to them and they will sort you and buster out