Chicken loosing feathers

Hi I was just hoping for some advice on my black sex link who has almost a saddle looking amount of her top feathers missing. She’s not even a year old and neither her or her sisters molted in the fall so I assumed it was something like that at first, like a late molt. But it’s been a bout a month and she hasn’t grow the feathers back or had pin feathers. We only have hens and I haven’t seen them fighting at all, so if anyone has any ideas I would really appreciate it.