I aggree with Garner about the Pedigree Chum food, I've come accross this many times with dogs, also I think 1-2 hours at night is far too much excercise for a puppy of that age, he only needs a couple of 10 minute a day walks. He needs to be put in the garden every hour and especially after food and play, make sure he gets lots of praise when he does it in the garden. A really good food for pups is Burns puppy food, they have a site which gives you a lot of information on how to feed your pup, there's no waste with this food so he won't be pooing so much but as Garner says you must do it gradually over a week or he'll be getting more upset tums. HTH