Sounds like a mite infestion. I'd dust her. The quill is the normal appearance of where new feathers are trying to erupt to replace shed feathers, but haven't grown out far enough yet. Have any other chickens been plucking at her? If not, I'd suspect mites.

Are these new feathers growing in after a molt? If so, they are normal and the bird will preen them in. Don't handle the bird during this time as it's painful for them. Offer some extra protein in the form of live mealworms/crickets, cooked ground beef, scrambled eggs, etc. to give them a protein boost--growing new feathers takes lots of protein!

Like calliope said, check her over for mites (tiny, dark, crawling specks, and/or grayish dust stuck to the base of feather shafts, which are the mite eggs). Place her on a sheet or two of white paper towels for about 20 mites, then look at the towels--mites are attracted to white and you'll see them crawling on the towels.

Also check to make sure she (or another bird) aren't pulling her feathers out. This can be a sign of boredom/overcrowding or a protein deficiency. If the feathers are being eaten after being pulled, offer more protein in their diet. Feather picking can be a tough bad habit to break, if that is what they are doing offer foods that take time to eat (a cabbage hung from a string, raw corn on the cob) to divert pecking from her and offer them entertainment. If they are overcrowded give them more room to roam.

Also, when growing new feathers they tend to be down-in-the-dumps and kinda grumpy, which is normal. Heck, I'd be grumpy, too!

Velvet ~:>