8 week old German Shepherd loose stool
I just got this puppy like 5 days ago and he is 8 weeks old and I noticed he was on Purina Puppy chow and i heard that dog food is crap and he was having lose stool and it was pretty persist for a few days so i switched his food to Nutro Lamb and rice. I know i should't have switched his food so quickly but his stool was lose on both foods so i didn't really think nothing of it so i took him to the vet. He got his stool tested and no parasites or worms so they sent me home with some medicine and some Hills i\d bland diet food and told me to feed him in small portions and so i did the medicine and food and he improved for a day so i mixed a little Nutro back into his food with the I\D food and he is now having lose stools(no blood). His energy is fine and appetite. Im not sure if i moved to fast with the normal food or what to do. Can i get some advice please?