Certianly take the dog to the vet, puppies can have some skin problems due to them crawling all over each other and transferring bacteria. It is very hard to keep puppies bacteria and parasite free. Keep them well bathed and clean. They may need anti...
Could also be geardia. It is contageous to humans. It is usually associated with drinking ground water. Suggest you get the dog to the vet. Also the poop has a horrible bloody smell like coccidia.