Hello. We have 3 chickens, Rhode Island Red, mendelshom blue and Coucou. They are 1.5 years old and have been together for this whole time (established flock). We had a 4th medelshom blue that was removed and put down in September last year. They have a run about 10metre square as well as the coop with roosts and nest boxes. All cleaned regularly. Access to fresh water and layers mash, as well as regular greens and safe scraps, rice etc. They are let our to free range while we're in the garden. The Rhode Island is very sick. She has always been bottom of the pecking order. Just after the 4th mendelshom was removed from the flock, she started to loose her feathers around tail and vent. It gradually got worse and she stopped laying. I thought it was her moult as the other had recently gone through this to a greater or lesser extent. We then noticed the other 2 were pecking and pulling at her feathers around this area. Over the last week she has gradually become less lively, not foraging as much when let out, not appearing as interested in food. 2 days ago the pecking increased and she was not moving away, she also went into the coop in the daytime and stood on the floor not moving, they never do this. I separated her out into a dog cage inside the run with fresh water food and treats. She just stood there with the occasional peck at food and not drinking. Yesterday I also felt her abdomen and couldn't feel an egg, but bathed her lowere half in warm water, tried to massage and put olive oil on her vent. I put her on the nestbox and she just stayed there stood up in the nest all night. I've brought her out in the dog cage in the run this morning, but she's just stood up and often closing her eyes. She ate a little food but no water. If I lift her out into the run, the other 2 immediately start pecking her and pulling her feathers out and eating them. She makes no effort to get away. I don't know if she's sick, and because she's the lowest in the pecking order they are attacking more as she's weakened, or if the pecking has made her ill. I'm worried she's going to die and don't know what else to do, any advice please? The other 2 are healthy, eating and laying with no missing feathers.