I clean our coop really well once a month and my ladies and gents are all free range so they’re only inside for laying eggs and nighttime.I noticed 3 of my girls have lost quite a few feathers and it’s even worse around the head and neck area. Some of the back of my mille and my red and blue Wyandotte is losing just loose looking fluff kind of throughout. She’s free ranging, eating and drinking, but I’m concerned. My barnevelder looks a little greasy around her neck area and has lost some feathers on the back of her neck/head too and they look pitiful! They’re only 9-10 months old so it can’t be molting right? These are my first chickens and I’ve had them since they were 2 days old so naturally I’m worried. I also thought maybe overmating with our roo, but it doesn’t seem like this would happen in the front of her neck too. Also, we changed their feed about 4 weeks ago. I don’t see any mites or love that I can find, but I notice lots of preening with most of them, some more than others. Out of my 22 chickens, this is just with 3 of them. Pictures are of Loretta, my Wyandotte. What should I try? Thanks in advance!