2 year old hen pulls out massive feathers mostly at night. Her chest is bald and her fancy pants are almost gone. No mites, but treated anyway just in case. She's a non setter, so not preparing her nest, and not molting. She's separated from the flock because she'll pull out all their feathers too. Strange behavior to say the least. I've increased her protein intake, mixed rolled oats in feed, and offer fresh greens daily. Nothing is working. Any suggestions?