I've noticed a few of my Golden Comets have red bottoms. They are missing feathers and the skin seems irritated. We looked to see if we saw any bugs and didnt notice anything but we did sprinkle DE in the coop just incase. All the hens lay regularly. Free range during the day and eat layena pellets and all seem to have normal behavior. I have noticed that some of their poop has been a little runny and super stinky. The photo of the chicken is the worst of the bunch. Some of them hardly have any redness, and our america has nothing which leads me think it isnt pests.