Hi, I have 26 hens and some are starting to lose or have lost the feathers around their vent and backside, others have lost feathers on their chest, and a couple have lost feathers around their tails and one on her head. We have changed their feed and given them other things to peck at... thinking maybe they were not getting correct nutrition or bored and pecking each other. There has recently been a decrease in egg production. Any suggestions on what we can do to help them? We have only had chickens for a couple years and have never had any issues before. Any suggestions are appreciated.