I found one of my rooster in the yard on his back. He was movinging his legs and trying but looked a truttle on its back. When i stood him up he would take s few steps then fall on his side. He would move his legs like he was trying to get up but made no progress. This has been about a week ago. I put him in a cage wiyh hay on both sides to keep him up. He is eating and drinking fine. Very alert. But if he falls over he cant get up. I do not know how old he is or anything abouy his past. I got him a two other roosters from the animal Shealter. All other chickens are fine. If ihold his tail feathers he can walk but seems stiff and unbalanced. Any ideas what it may be?