Looking like a porcupine!

Thanks in advance to anyone who replies with ideas for me. I thought my hens had gone through their molt in Oct/Nov, but the past two weeks have seen one of my "little red hens" suddenly go bare on the back of her neck and around the part where her hackles grew. Well, not exactly bare. All the feather shafts are there, making her look rather porcupine-ish, but the feathers are gone. At first I thought one of the hens was pecking at her when they were roosting at night since I did not see any peckish behavior during the day. Lots of red feathers can be seen around the coop and surrounding yard. She doesn't look like my BR hen looks, the one that has been consistently pecked on her back and shoulders since arriving here as a rescue hen in the summer. The BR is absolutely bare in places that are red looking--not bloody, but irritated looking. (BTW, I'm thinking of getting some Blue Kote to apply on her to see if hiding the highly visible red will slow down and stop the abuse.) But, back to my little red hen, as fall went on, she became fuller in form, shiny feathered, looking so good we renamed her Show Girl...and now this feather loss. I'd think she'd freeze in our freezing temps we're having now, but she roams and carries on as usual, just with feather shafts instead of feathers. Late or second molt or being picked on? Thanks for your diagnosis! ~G