I'm thinking about switching Finn to a different flavor of the same food he eats now. He loves his food but with the tummy issues he's been having I thought maybe a change if flavor would help. The vet said it's possible that the chicken flavor he has is not agreeing with him so I suppose it wouldn't hurt to go with lamb or fish. My question is, since he would be eating the same brand, same formula just different flavor would we still need to mix it in gradually or not?