Can anyone please help? I have a flock of 20 chickens right now. We lost an Americauna hen about a month ago we never could figure out what happened it turned cold she just tucked her head in and died. We tried to keep her warm but it didn't seem to help. About a week ago one of the RIR hens came down with a respiratory cold. I isolated her from the rest of the flock wormed her to make sure there was no gapeworm with ivermectrin and treated her with Tylan-50 for 5 days and gave probiotics in her water. Now a week later I was in their yard feeding treats this morning and noticed a have a Barred Rock picking her legs up awkwardly and having to sit alot. She still has an appetite and is drinking I also have isolated her. Any ideas on what is going on? All of these chickens are approximately 1 year old. I know we have had a colder winter and a wet one as well. Also, after removal of the chicken with the respiratory issues I scrubbed the inside of their coop down and sprayed with hydrogen peroxide, all new bedding and I am putting supplemental vitamins in their water. Any help would be greatly appreciated.