We have a yearling bull that has a growth on his head right behind the poll. Right at birth, it looked like a small tear or hole in the hide in that spot. It grew to a pink lump. It has been there ever since. It occasionally bleeds, drains pus and crusts over with a black crust. We have removed it and when we did it looked like it was made up of "soft grains of sand". It grew back. We have tried many topical treatments as well. Does anyone know what this is and how to get rid of it because he is a purebred bull that we would like to sell this spring, but we don't want to sell him like that, even though it has never bothered him or get any bigger or anything, it is just ugly and smelly.