4 mo old nh red with skin problem?

[jeeperspeepers2010]

Hoping someone might be able to help me. Just noticed today that my 4 month old NH red has missing tail feathers and looks like she has been pecked at. The sore is crusted over but the other hens and she herself pick at the area that is crusted over and at the surrounding feathers. Does anyone have any idea as to what is going on? Help please.
Thanks