Sorry about your limping hen. If you are good at YouTube videos, you can upload a short one of her walking, and post it here. Injury is usually the first thing to rule out with limping. If she jumped and landed wrong, or if was mated or jumped on by a heavy rooster. Vitamin B2 deficiency is another problem to rule out, and treat. Does she have problems with balance or try to put her foot down and it seems numb? Mareks disease is something that may cause that. The hard breathing could be related. Make sure that she can get to food and water. Watch out that she is not pecked or hurt by other chickens, who typically will attack when they see illness. You might need to separate her, both for forcing her to rest, and to watch her carefully. Do you know if she was vaccinated for Mareks?
