My chicken has a similar issue and this is the second time it has happened in a few months. My 8 month old Wyandotte got so bad that she could barely walk but I gave her water with ACV and fresh sliced garlic for a few weeks and she seemed to have snapped out of it. I know my flock was exposed to Marek's so this may be manifestation of the disease and I will have to consider culling her soon. Do you know if your chicks were vaccinated for Marek's within the first 36 hours of hatching? I hope your bird doesn't have it because its very sad to loose birds after you have worked so hard to raise them! I have already lost 3 of my birds to Marek's and will probably loose a few more. Don't buy your chicks from Russell at Chickens Galore in Norco, CA. He does not vaccinate his chicks for Marek's and the birds I got from him are the ones that are dying.