It looks like one of her flock mates has been chewing on her developing flight feathers or drakes have been gang breeding her. I would monitor very closely - probably even separate her from the flock when I could not observe them.
Poor baby something has really been after her. If she isn't laying age she should not even be in with drakes.
Clean her up real good and place her and another female together separated form the rest but where all can still see each other. Just make sure who ever you put in with her for company isn't abusing her.