Hi rme147,
Breeders normally dock Corgi pups tails around 3 days of age. Their tail is so tiny at that point, that it's hard to imagine that they would feel more than a little pinch. His "lack of tail" should not be painful.
Sounds like he is sitting ok. When you talk about seeing other dogs drag around on their rear...that's usually a sign of tapeworm or hookworm.
Welcome! Enjoy the forums.
