I have a 16 week white leghorn roo. He grew extremely quickly-twice the size of my hens and had full comb and wattles by 8 weeks. He now walks like he is arthritic. He has a very stiff gate when he walks. I have checked his feet. No sign of bumblefoot. He spends much of his time lieing down and leaning forward. He is eating and drinking. I have put antibiotic and vitamins in their water. The hens appear to be fine. Any advice or solutions??? Thanks.