Do you know what the breeder was feeding and have you offered it to him? It is best to stick with the same thing if possible. In most cases, the worst thing you can do is offer a none eater a variety of rich food to tempt it into eating. If the puppy is otherwise active, clear eyes, and a cold nose, I see no reason to run to the vet.
As I mention in in the sticky under ''What does a puppy need?'',
http://www.askmehelpdesk.com/dogs/in...tml#post251802 you do need to schedule a vet visit soon to continue the shot program the breeder should have started. You should look at the ''My dog won't eat'' topic too. Puppies commonly come from the breeder too fat, and a day or 2 without eating won't hurt anything.