I wish I knew something about gape worms, but I've been fortunate enough so far to not have to know about gape worms! Hopefully someone can explain the symptoms a little bit.
Is it possible that he's molting? One of my hen's was shaking her head and doing that gaping thing with her mouth a little more than normal about a month ago and it turned out she was molting and swallowing a lot of her feathers when she groomed herself.
i say...i say now, boy, why u wanna? i say, why you wanna go on shakin and a twitchin I said a twitchin, your head like that. ain't ya? i say ain't ya got no sense?
Gape worms can be seen in the trachea. They're red and forked.
How often does he shake his head? And by shake, do you mean swaying or shaking/shivering/vibrating? Large roosters like to shake their heads from side to side. It's a cocky thing. They do it to shake their wattles. Lol. It's pretty cute. If it's only the rooster that's shaking, I'd say he's just airing out his wattles.
in my case its like a quick twitch, they do it for a while a few minutes then dont do it at all on second thought they do it alot.......i seriously thought it was their down tickling them as it was coming out