I am new to GSDs. I have an 11 week old puppy who i got at 8 weeks. Breeder had her on diamond naturals large breed puppy. They gave me a small baggie to transition to new food. I got natural balance large breed puppy to adult. She was given a dewormer the Wednesday before i brought her home an came home that Saturday. Went to the vet (not our usual) the following Monday. Was given heartguard and was told heavy load of round worms, but heartguard would help. Diarrhea got worse around Friday but figured it was from dewormer and heartguard. She started vomiting blood Saturday morning so we went to our normal vet. Tested for parvo wich was negative but still round worms. They gave her fluids, special wet food, another dewormer, and antibiotics thinking everything was from the parasites. A week later we were back to very watery diarrhea and no energy. Back to vet. Almost no sign of woms or other parasites. Suspect food sensitivity so gave Royal Canin GI puppy dry food and probiotics. Diarrhea got better very next day. She has been doing better except will get softer stools here and there. Not sure if it is her treats we use for obedience class or what. Vomited a little blood along with dirt she ate (we didn't know she ate it) this past Monday. Vet thinks its an ulcer and gave meds. The GI food is expensive but seems to help. Any thoughts or insights would be greatly appreciated. Sorry it's so long.