This is the second sore that has appeared on our turken. The first was on her chest. I thought she had scraped herself or injured herself in some way until I noticed this one show up. The other one is totally gone. It got smaller and smaller over the course of about a week until it was gone. She is acting normal and laying.
We adopted a kitten from a shelter and recently discovered it has ringworm. The two have had no direct contact as the kitten is indoor and the chickens are all outside. But this is the only thing I can think of.