Get Your Dog Care Questions Answered by Experts
It sounds like your dog is suffering from something that is often referred to as "happy tail." The best and sometimes the most fastidious treatment IS docking the tail but there are some other ways that you can try.
Some people get good results from loosely taping a baby sock over the end of the tail. This protects it from injury while it's healing.
Other people get good results by lightly bandaging the tail between the legs so that it swings freely but not hard enough to bump into anything. There is a method by which you can wrap around the legs and "capture" the tail, keeping it from swinging so that the end result is no more damage to the tail. Your vet can help you learn this wrapping procedure.
The problem is that blood supply to the end of the tail is low so it can take some time to heal, seemingly forever.
I hope this helps!
Let me know if you have more questions or if you want to discuss this further. I would be happy to help.