Swollen Tail - Cocker Spaniel

[canddgreenwood]

My mother has a 10 year old Cocker Spaniel and within the last week it has developed a very swollen tail. The tail appears to have scabs on the end of it as well as where the tail attaches to the body, the skin seems raw.
There has been no change to the dogs diet, and the dog has had no run ins with other animals.
The dog does not appear to be in any pain, although he does chew at his tail now.
My mother has put some salve on it that seems to comfort the dog, but what could be the cause of this??
Is this a sympton of something else??
My mother did take the dog to the vet, but she lives in a small town, and the vet said he was unsure.
Is there anything we can do to assist the dog? Has anyone else had this experience with their dog or cocker spaniel in particular??
Thank you