That’s odd, a pic or video could be helpful. When is the last deworming? Clean coop? Any weird treats or new roaming space? It could be something internal, or the leg. Is it swollen? Is he limping, and do you have other roosters ?
The babies were super healthy, a boy and a girl, and they both went on to find wonderful homes! So did the mom! I can’t update as she was a foster, not mine ❤️