Our dog was in his playpen when my kids came home from school and noticed that he was biting his tail to the point that it had started to bleed. I call the Vet and we got him in to be looked at. The vet thought that it was a skin infection and provided antibiotics and pain medication. A couple of days later I noticed that he was still in pain and still attacking his tail even with the cone on. That is when they realized that his tail bone was broken and part was now hanging by a few ligament. He now needs surgery to have it properly removed it so it does not cause an infection to spread.
Any help is much appreciated.