Just yesterday around 430 pm I notice one of our hens laying down in the middle of our run with her feet curled and eyes tired. She had some white mucus discharge out of her back end. She was also tipping side to side and arching her back and neck. When I inspected her she seemed to have a lump underneath her tail on the left side. When she did try to make it to the coop she wobbled dragging her back end and I had to set her in the nesting box. She did not make it through the night. If it was an egg it would've been her first. What else could've happened. Our two other hens seem healthy.