I have four chickens that are about 1 year old. They have always gotten along great and never fought. They have freedom, space, lots of different kinds of foods. Today for the first time one of them attacked another. Every time they are together she attacks. I have separated the fighter from the group. She is super upset. She can see her sisters but is in a different coop alone. She was very upset so i put her back with her sisters and she immediately attacked the other chicken again. Not sure what to do. Should i leave her by herself? put just one chicken with her? Please help.