Rooster with Mystery Leg Injury

Last August, I hatched 3 chicks, and two grew up to be some of the friendliest roosters that I've ever had. Today, one of them inexplicably went lame. As I was getting ready to put his brother in for the evening, I noticed that he was limping to the point where he was hopping on his right leg, not using his left leg at all.

Things that have been mostly ruled out:
-Fracture from ankle and below. There is no sign of any broken bones on his calf or the portion of his leg not covered in feathers.
-Paralysis in left leg. He can move it when he wants to and pull it up to stand like a flamingo, and my flock has no history of Marek's disease.
-Foot wound. His foot was the first thing I checked. No sign of a wound.

Possible possibilities. I don't know how to recognize these, nor do I know how common they are in less-than-one-year-old roosters who haven't been doing any particularly strenuous activities:
-Hip or thigh fracture
-Sprain
-Strained muscle
-Ligament damage
-Dark magic

If you know how to recognize symptoms to any of those, how I can tell, what I can do, and the recovery rate, I would greatly like to know. If it would help, here are a few things about his physiology and behavior:
-Not quite as big as most standard breeds (he's a mutt), but definitely bigger than a bantam
-Built light, but probably not underweight
-Very easily handled. Submits freely to being held on his back, content when picked up
-Enjoys flying. He likes perching in high places and is one of only 3 chickens I have had who has slept in a tree.
-Somewhat responsive to "Louie" and "Who's a good boy"

If there's anything I can do to figure out his ailment and/or help him heal, I would like to hear soon. I currently have him confined in a rabbit hutch with food and water and a hay bed he doesn't show much interest in sleeping on. Please reply if you have and advice on how I can help him, as I lack access to a veterinarian.

Just my thoughts here...since he is a flyer and likes to perch in high places, I would suspect a sprain or strain of some sort, from jumping down or landing wrong.
The best thing to do is limit his activities for several days, hence the 'ol rabbit hutch will be jail (bummer I know). Provide him with food and water (you can add some Bvitamins to the water if you wish), give some treats/fruit, veggies, bugs and see if confinement makes any improvement.

Here's a few links that may be helpful.
https://www.backyardchickens.com/a/leg-foot-and-toe-issues-in-poultry-of-all-ages
https://sites.google.com/a/poultrypedia.com/poultrypedia/poultry-podiatry

It could easily be possible that he sprained something when landing.

Meanwhile, about 20 hours later, he is doing at least a little better. He seems to be trying to walk on his leg, which means progress, but also the pressure could delay healing. i tried feeling for any hot areas on his leg, which would indicate the location of injury, but he was being a little squirmy as he stood in the rabbit hutch and it was difficult to detect and temperature changes through his down. He remains restrained to the rabbit hutch.

Poor thing. I didn't think he would like jail