Have you heard of Marek's disease? Sounds like it may be that. My rooster has been doing the same thing for a week. I had a vet do blood work, waiting to hear. It is a disease where tumors grow in the nerves causing numbness, sometimes paralysis, sometimes death. I'm still learning about it myself. It breaks my heart to watch him hop over to where his girls are. He can't scratch so he pecks at all that they scratch up. The good thing is he is not in any pain. But I can't imagine his good leg not starting to hurt from all the weight being on it.
Do you have an aviary vet or farm vet? I would definitely get him/her checked out. I have been giving my rooster anti-inflammatory shot since Friday. He seems to be putting a little more weight on his leg, but he's still limping.
