Daisy - I got your PM and came here to find your thread!
This is EXACTLY what my hen looked like! Her toes curled up, and she appeared to have no control over her legs, although they were not paralyzed. She "could" move them and clench her toes and whatnot, but she could not stand up and support her own weight. She would try and she could sit down on the hock joint in the leg, but could not stand all the way up. If she got too tired, she'd tip forward onto her chest, or even onto her side.
My hen is doing excellent now! She is about 99% back to normal. She has a tiny bit of residual weakness, but it is very very minor and hardly noticeable.
When my avian vet saw her, he thought calcium deficiency right away. So that might definitely be worth a try.
I was also giving her a general vitamin/mineral powder mixed in her water (I can't recall the name right now. I bought it at the farm store.) That way she was getting B vitamins too, in case that was part of the problem.
My hen did not act "sick" and what I've read is that with Mareks or Botulism, they will appear more run down and stressed since there is an actual disease process occuring. My hen ate and drank and tried to preen her feathers. If I put her out on the grass, she would sometimes tip right over on her side with her legs stuck straight out. I would have to keep setting her upright. I did not think a chicken could ever recover from something like that, but she did!
The curled up toes was one thing the vet noted as being associated with calcium deficiency. It affects their ability to flex and contract the muscles so the toes get curled up and it is hard for them to uncurl them.
Cheese in high in calcium, and especially if you get a bright yellow cheddar cheese, and cut it into tiny bits, she might try to eat that also. Green leafy vegetables is good. I also fed my hen meat, which doesn't have calcium but I figured it would give her energy and extra protein. She loved shredded tuna, and even cooked chicken. Didn't really eat the hamburger I gave her.
He told me if she would not eat foods coated in the Osteo-Form powder, that I would need to mix it with a little yogurt and water and syringe it down her. I was supposed to get 1/4 tsp. into her every day. But I had good luck with her eating foods coated in the powder.
My total cost was $140 dollars at the vet, and that included some blood work and antibiotics.
PLEASE keep us updated on what happens, and how you end up treating your poor bird!