Hello Mrs. Cooper,
I am sorry to hear that your dog is having these problems.
Many times, allergies will show up like you are describing, with a dog itching, so he would lick or chew, or even drag himself to scratch himself.
Here is a link to an article on allergies and itching in dogs:
There can also be a problem with the anal glands that causes this itching, particularly at the anus, and will cause a dog to scoot his botXXXXX XXXXXke you describe.
Here is a link to an article on anal gland problems:
We can also see dogs scooting the back end along the ground in instances of intestinal parasite infestations. Having a fecal sample tested with your veterinarian is always a good idea!
I hope this helps!
As always, if you have further questions or concerns, please don't hesitate to ask them using the "reply" function.