I just noticed our only leghorn very droopy and lethargic. She doesn't seem interested in the chopped corn I fed the flock as a treat. She has been our most reliable layer-. usually we get an egg a day from her, but it has been several days since we have had any eggs from her. We have a mixed herd of bantams, brown hens, Marano mix-about 20 chickens total of varying ages and 2 roosters about 5 mo old.She has a very soiled vent area and a few missing feathers. I have not noticed her poop. She just looks like she doesn't feel good. Any suggestions?