I had six barred rocks 5 months old. Earlier this week I went out and one was down and couldnt walk. I ended up having to put her down. I go out there today and one is dead and another one is sitting down instead of standing up and every time I would get her up she would sit back down. Comb and waddles very pale, and feet are cold. no discharge from the nose, no sneezing, no coughing or respiratory issues at all as far as I can tell. Any help would be appreciated.