Is that her back or front? Do you have a rooster?
She may be being overbred by the roosters.
Yes, if you have a rooster, you might want to separate him or get more girls to spread the love around. They sell chicken "saddles" to protect the hen's back.
Could she be molting? Some extra protein in their diet could help if she is or if the other hens are feather picking. Most layer feed has the bare minimum of protein.
Looks like rooster damage.
You can purchase hen saddles here: www.hensaver.com
Pattern to make your own here: http://www.backyardchickens.com/t/424354/free-chicken-apron-saddle-pattern
I make mine from sunbrella fabric.