Whether or not it's gout, and that would have been my guess on the feet also, she's being attacked by the others because they sense illness or weakness. If she's only laid once at 9 months old (was the egg normal?) then she may have a reproductive problem also. I would separate her, monitor eating, drinking, what droppings look like. Give her a good going over, check weight/body condition, monitor crop function to make sure she's digesting correctly, feel her abdomen for any bloat or swelling, water balloon like or very hard (compare with others if you aren't sure). Try the sour cherry recommended and see if it brings any improvement with her feet.