Background: I have 1 fenced in acre, and all my chickens free range during the day, and stay in the coop at night. My favorite hen (the sick one) has always been pecked on by the others in the coop. Over the last few weeks, all my chickens have molted. This particular hen just seems to be losing feathers though -- not quite like molting. She's not bald anywhere (we went through that already this summer with the same hen), but the feathers are ratty looking on her wings, and her long tail feathers aren't there. She pooped yellow the other day, and I assumed this meant she had worms, so I did the paste treatment of ivermectin. I was told this wouldn't work, so I'm waiting until next Sunday so I don't overdose them, and doing the Wazine? Yesterday I noticed her comb was VERY pale compared to the others. She is free ranging today and active around the yard. . .just doesn't look too hot. What could be causing this?