there is a strange lump at the base of his tail what could it be?

My dog has a lump at the base of his tail it looks like a raised Mole i have arranged an appointment with the vet for the next available appointment which is tomorrow, it's itchy as he has been scratching it and the other day it was bleeding... it's now shrunk, when i was trying to examine it closer i noticed little black specks near it... they are solid and felt like dirt.... what do you think it is ? a skin condition?

could be parasitic. could be a little cancer depending on how old your dog is. could be an infected scratch. hard to say without seeing it for sure. could be an infected hair follicle. Lucky dog to have a guardian who is so on the ball, many don't have that. Good luck and please don't worry until the vet has seen it. if the dog is a chinese crested it is likely a pimple.