This could be a dumb question, but I figured it didn't hurt to ask. I got chicks at tractor supply just over 3 weeks ago. They looked just like my previous chicks so I assumed they were white plymouth rocks. They came from the pullet bin. Well one of the chicks has started developing a brown blotch of feathers on each wing. The quills in those area are brown too, almost like they have blood in them. I'm not sure if she's just a weirdly colored chick or this should be something I should be worried about. 4 of the chicks are straight white. One other has a couple tiny feathers on each wing that look a little brown too. I don't have a very good camera, but I'll try to attach a couple pics.
https://www.backyardchickens.com/g/i/5598222/default/
https://www.backyardchickens.com/g/i/5598222/default/