Bantam rooster can't stand or walk!

[ManiCraft]

Hi everyone!
We have a few chickens, and this morning, we noticed that one of our bantam roosters is just lying there, with its legs out from under it. He couldn't stand up.
He is a few months old and we brought him inside, and he ate and drank.
What could it be?

Possible:
Spinal injury, the dog stepped on him a week ago, but he was fine, could the others crush his back?
Marek's is doubtful, since he is eating, and no other chicken has symptoms.
I would rule out vitamin deficiencies, because they are free range and we regularly give them supplements.

 

[All4Eggz]

Hi everyone!
We have a few chickens, and this morning, we noticed that one of our bantam roosters is just lying there, with its legs out from under it. He couldn't stand up.
He is a few months old and we brought him inside, and he ate and drank.
What could it be?

Possible:
Spinal injury, the dog stepped on him a week ago, but he was fine, could the others crush his back?
Marek's is doubtful, since he is eating, and no other chicken has symptoms.
I would rule out vitamin deficiencies, because they are free range and we regularly give them supplements.

Splayed legs maybe?

 

[ManiCraft]

Splayed legs maybe?

Isn't he a little too old for that?
We've had it happen to chicks, but isn't it caused by weak leg muscles. We rubbed banded their legs together and they got better.

 

[Eggcessive]

Separate him in a wire dog crate near food and water. Prop him up on rolled towels or try a chicken sling. He may have been hurt, or it could be a disease, such as Mareks. Aspirin can be used for inflammation and pain. Note if he can move either leg or toes. Vitamins including riboflavin can be given daily.

 

[ManiCraft]

Separate him in a wire dog crate near food and water. Prop him up on rolled towels or try a chicken sling. He may have been hurt, or it could be a disease, such as Mareks. Aspirin can be used for inflammation and pain. Note if he can move either leg or toes. Vitamins including riboflavin can be given daily.

We did put him in a sling a couple hours ago, and he ate and drank in it, he sometimes moves his tail feathers and I think that when we put him into the sling, I saw his leg twitch.

 

[Wyorp Rock]

Hi everyone!
We have a few chickens, and this morning, we noticed that one of our bantam roosters is just lying there, with its legs out from under it. He couldn't stand up.
He is a few months old and we brought him inside, and he ate and drank.
What could it be?

Possible:
Spinal injury, the dog stepped on him a week ago, but he was fine, could the others crush his back?
Marek's is doubtful, since he is eating, and no other chicken has symptoms.
I would rule out vitamin deficiencies, because they are free range and we regularly give them supplements.

Can you post some photos of him?
What do you feed?

 

[ManiCraft]

Can you post some photos of him?
What do you feed?

I made an update post, you can find answers there