Her lower belly looks enlarged possibly from water belly or a reproductive disorder, such as salpingitis. I would also recommend Hibiclens or chlorhexidene which can be found at Walmart in the bandaid aisle for about $10. You apply a small amount mixed with half water, and then rinse it off. Saline is also fine to use, but use the antibiotic ointment after and keep it open to air. A wire dog crate with food and water is a good way to separate her in view of the flock. Keep her away from flies with can deposit maggot larvae into the wound during warm weather resulting in serious fly strike. Scratch and peck feeds may not be the best thing for her. They tend to pick out the most appealing parts, leaving some of the added nutrients. When I tried one, they left the powdery parts in the feeder. I prefer a homogeneous all flock or layer feed, crumbles or pellets where each bite is well balanced.