Any updates on this puppy?
Is he nursing, peeing and dedicating? Is the mother licking him to stimulate him? If not, you need to and make sure he is going. I never wormed puppies at 2weeks. What wormer did you use and how much? There are a couple of things I would try but would not advise here as I am not qualified to. Have you tried burping him, patting him on the back and sides lightly? If it were me, I think I would be at the Vet's and soon!!