One of my chickens, who is about 2 years old, has become sick. She has been sick for 7 days now and seemed to start getting better (day 2-3), but now had started going downhill again (day 5-7). I have been doing research based on her symptoms to come to a diagnosis to treat her properly, but have been unsuccessful. She is lethargic and doesn't move much but will stand up. Her tail feathers are tilted down and her wings are dropping. The area on her face around her eyes and beak looks shriveled and scaly. This symptom started within the past 2 days. The second day of being sick her comb was purplish-blue at the edges and shriveled, but this went away within a day after I brought her inside. Her poop is abnormal in that the white part is very loose and there's a cylindrical, relatively solid piece that is brownish-green. She's been eating and drinking some whenever I dip her beak in the water. I have started treating (2 days) Corid for Cocci, but have not seen an improvement yet. I have not seen any blood in her stools, so I'm not sure she has Cocci. I have been giving her greek yogurt and soaking a few pieces of her regular food in it and she will eat a little bit at a time. She's lost weight over the past week from not eating much and feels very light. I've been giving her vitamins in her water as well. I have 5 other chickens which aren't showing any signs of sickness. I would really appreciate any suggests or help with diagnosing her and figuring out a treatment.