I was wondering how your little dog is doing. I worm my dogs with the pet wormer and they have no problems with it as they are 70 and 80 lbs. But I have a little cat, who only weighs 4 lbs. At the beginning she broke out with little bumps all over her body and had intense itching. The next month when I gave her the wormer I just gave her the smallest pinch ever. Like mere grains...wouldn't make 1/16 of a teaspoon probably. Then instead of dividing it up three times a day, I gave it too her four times a day. This seemed to work for her and the bumps and itching never came back. I think that perhaps she was experiencing some heavy die-off the first time.
Dogs and cats always seek grass out when they feel ill. You can purchase a little pot of grass at a pet food store for them to munch on. I've seen them in the cat section of the stores. Maybe this will help your little pup. I know how hard it is to see one of our furry companions ill.