I have 4 barred rocks who are just wonderful. One of them is a little lighter in color than the others. She has some bare patches on her breast that show very red skin. Also on her bottom below her vent is become bare and red. I don't notice anyone picking on her and her coop is covered so I don't think the sun is bothering her. She has been this way for a couple of weeks at least and it the bare patches seem to getting bigger. All 4 of the hens are about 18 months old and are finishing their first year laying. She is normal in every other way. Anyone have any ideas?