I have a 17.2 hand percheron and she has had a sore on her fetlock for.....well a long time,too long.I have had the vet look at it and he said to scrub it with a veggie scrub brush then put cut and heal powder on it.I have been doing that,and yet it still won't go away.And it gets gooey and smelly.should I wrap it or leave it or should I be trying something completely different?