My black silkie hen (about 9 months old) has these horrible crusty white feet. My first thought was scaly leg mites so I washed them with diluted tea tree oil, wintergreen rubbing alcohol, with a bristle brush, and rubbed them with vaseline. That was a week ago and they're still the same. I don't really see any scales standing up, but rather white crusty stuff on top. My other 9 hens and 1 rooster don't have any signs of this or scaley mites. Can anyone guess what this is and what I can do? Do you think I should try the injectable ivomec mentioned on other posts?