I don't know what to do..HELP!
How long have the cockerels been gone? Were they challenging your rooster or fighting with him. It can be chaotic with a bunch of juveniles starting up with their hormones. I had a similar situation once where the young ones "overthrew" their father when they were starting to try to mate. He regained his place as head of the flock when the younger ones were gone. Hopefully your rooster didn't injure his legs or suffer a head injury. Mareks disease is something that affect balance and cause paralysis in one or both legs or wings. Was he vaccinated for Mareks? Usually it strikes younger chickens under 6-7 months, but it can strike older birds if they are exposed to it by a carrier. Is he eating and drinking normally? Dehydration or being kept from food can affect balance and strength. Put some vitamins in his water or give him 3 mls of Poultry Nutri-drench or Poultry Cell daily to see if he perks up.