My 1 year old Toby has always been picky about what he eats and has a sensitive stomach. Well he was sick last weekend and I took him to the vet and they gave him a special Purina food diherea. It was can food and he loved it. They gave me four cans and said to give him that and then use his old food (BilJac) but he hasn't ate since I stopped using the Purina. I don't know if I should change his food or what. What do yall think?