I have a 7 week old full blooded Lab puppy. He is the runt of the litter. While the pups were still getting just milk he was doing ok,but now that they are weaned they get fed canned dog food.The rest of the pups eat it fine and they are all fat and healthy. He didnt eat anything for a few days then we tried different brand of food and he only eats a few bites a couple times a day. All the pups have been wormed and he has been wormed twice. They will get their first shots in a week or so. He is energetic,playful.He drinks good. Is it just that he doesnt like the food or is he sick?