Hi, I am new to chickens and we have had two from about April time.I would appreciate any help with this problem as i have asked several other chicken owners locally and no one has experienced this issue. They were about 20 weeks old when we got them and two weeks ago one (Wilma) started to be very lethargic and stopped eating. We let them out for a few hours each day and Wilma would just stand looking very sorry for herself rather than her usual madcap dash about. Her comb went to a gray colour she stopped laying and her poop contains what looks like egg yolk where it would normally be white. I did give her a vitamin tonic which did perk her up and now she seems to run around happily and eats and drinks though not so much , but is still off colour, not laying and her poop has not changed. Does anyone have any ideas. The other bird is fine . Thank you.