Chicken won't walk, put weight on legs.

[sublme]

Recently had a chicken that won't put weight on legs or walk, flaps wings to get around. Eats and drinks otherwise seems fine. When laying down uses wings to balance herself and feet are somewhat curled over. I have attached some pictures of her and her poop. Poop looks weird. This has been going on for 2 weeks.

 

[Sussex19]

Has there been any incident, i.e. a dog or other animal attack?
If this just developed be its self, I would be concerned that it could be marak's.
How old is she, and have you had any other chickens with similar symptoms?

 

[sublme]

Nothing incident related, they stay in their coop and run. 5 months. All the other chickens are fine, 7 total, she is only with this issue. First started with her limping and not using one leg, then wouldn't stand on either. Seems neurological than physical. Also seems that she has a hard time focusing as her eyes dilate then go back to normal.

She was vaccinated for marek's.

 

[Sussex19]

As she's vaccinated, it's less likely, but doesn't completely rule it out.
Hopefully more experienced people will come along, and might have more suggestions.
In this thread https://www.backyardchickens.com/threads/ocular-mareks.1395842/ there's some photos of what ocular marak's look like.