Hello, and welcome to the BYC community. The sad reality is that your cockerel's issues are a result of his DNA. Keep him as comfortable as possible, but there is a sadly short limit to his lifespan.
I had a young male who had difficulty walking. I took a shallow tub and put some hay in it to make him a bed and he knew that was his spot. He did eventually get better. You will find a lot of good information here Good luck and have fun...