Speckled Sussex doing poorly :(

[speisman]

I have an 11 month old speckled sussex hen that is not thriving. I don't think she has ever started laying. I found her in the coop lying down in an icy puddle ten days ago so I brought her inside to warm up. She will not stand on her own. Her comb and feet look normal, she eats and drinks, and poop is normal. She eats regular layer pellets, and will go after broccoli or watermelon as a treat. But she cannot stand at all - she is always lying down. I suspected Marek's but she doesn't seem to be getting any worse. No other chickens in the flock have this issue. What can I do to help her?

 

[Stipenvlerk]

Poor Chicken..
Did you take her to a vet?
How is she doing now?