Chicken pulling her own feathers out (pics included)

[denco5]

My EE is pulling out her feathers on her back, what is the issue and how can I cure it? I have 18 chickens and she is the only one with the issue. It is not a breeding issue as we see her pulling them out on her own.

 

[wren]

Make sure she doesn't have parasites. I'd treat the whole flock with spray on frontline. It looks a little sore, I'd put some blu kote on it too. It could be that she is stressed or missing something in her diet and is more sensitive to the lack than the others. I'd try switching to kent multi flock. It has more protein in it. Good luck!