Rooster with a limp/droopy behind.

[coffeeshopgirl7]

My two year old rooster started limping a couple days ago. He is still eating, drinking, and crowing. He doesn't seem listless or sick, he's just having a really hard time walking. I've checked his feet and he doesn't show any signs of bumblefoot or any injuries. His scales are fine, his toes seem to be fine, there really doesn't seem to be anything obvious wrong with him.
This evening we put him in the isolation cage inside the coop with the hens, so that he will stay off that leg but he won't be lonely. Is that the right thing to do? Is there anything else I should be doing or checking for? Here is a video of his sad little walk:

 

[willowbranchfarm]

Could he have fractured it??

 

[coffeeshopgirl7]

Sorry for the long absence.

He could have, I'm sure, but I didn't see it happen if he did. Despite plenty of roosting room at three different levels my chicks like to push each other off the roost right before bedtime. It's possible he landed badly. We felt up and down his leg and nothing felt wrong, or warm, and he didn't react in any way. After 6 days of resting in the cage, plenty of food and water, and staying in the warm coop (temps have been pretty low here) he hasn't shown any signs of recovery. I let him out into the yard today to socialize and get some air and exercise, and he hobbled over to the food and sat down like a hen laying, and ate some food. Then he went to fence and just sat there. I let the others out to free range and he didn't show any interest. We are deciding whether it's worth a costly trip to the vet just for them to tell us there is nothing they can do and we have to put him down.
Anymore ideas are greatly appreciated.