My 4.5 months old cockerel was fine until a week ago.one day, he just couldnt walk and kept his right leg bent as if he is too weak to support himself. There is no visible injury. He stays very low and sits down the moment I touch him. When he walks, he limps with apparent difficult. His left leg seems to be fine. I tried feeding him fish oil capsules but nothing happened. Its been like this for a week. Help?!!?