Read about Mareks and about many other things it can be. My place is very secure as I have no chicken friends for cross contamination and I don't bring in adult birds. I haven't had any changes in my chickens until this last batch of chicks in a very long time.View attachment 1235807 I will just have to wait and see. Everyone was fine yesterday. She is a big pullet.
I would be worried it's Mareks Disease. It isn't only spread by chickens, it can be spread by wild birds in their dander. It is highly contagious if that is what it is so I would be safe and cull a bird with those symptoms. I'm so sorry Red Banks.