How to stop mare from rubbing her tail?

Get a hold of a small clump of hair between your thumb and forefinger, hold it tight and very close to the skin and pull as you roll it over for finger. if you pull hard enough it will pop as if someone was popping their knuckles. Do that all over the area that she is rubbing. It must loosen the skin off the tail head, I have done this beforfe and it worked for me.