My oldest and dominant hen, Shelly is suddenly being bullied. I have 9 hens in a very large ( 27 foot x 9 foot) run and a large coop. They are always fed, get treats, and lots of water. The 1 year old Barred rocks (2 of them) that I have are now bullying her. For the past 3 days, she hides in the coop or runs around the run and flies onto the outside roost to get away from them. I don't know what to do for her. She seems scared of everything now, which is not like her because she was always the one who went after any new hens first. Any advice as to why this is happening? I am worrying about her. Thank you.