Dark black spots on your dog's paw could be the result of numerous problems. It's almost impossible for me to make an accurate suggestion on here, without seeing the extent of the spots.
The only advice I can give you is to take your dog to the veterinary practice, where they will be able to perform a thorough investigation of the problem.
Hopefully, the vet will be able to make a diagnosis immediately and start treatment right away.
What are these black spots on my dog's paw?
The best prediction I can make from the information provided is that your dog has an allergy. Allergies can sometimes cause irritation of the paws, and this will cause your dog to scratch the area - causing black scabs or spots.
The more unlikely reason could be that these black spots are the result of a more serious skin condition.
I would advise you to take your dog to the vets as soon as you can.