If it is a vitamin B deficiency, like what happened with my EE, I crushed up a B-50, mixed it with a tiny bit of yogurt, and gave her as much as I could 3 times daily. By the 2nd dose (aobut 6 hours after the first), she was finally able to stand without falling on her haunches and her toes started to uncurl. She's fine today, well, except I think she is a he.
Search for vitamin B therapy to read about the stories of others.
I switched food after this since a decent food shouldn't allow a deficiency to occur. I ditched the junky Nutrena and started feeding a locally made organic food.
Good luck!
ETA: Others suggest getting the infant Poly-vi-sol drops without iron at a pharmacy. Dribble some along the beak to encourage her to swallow, making sure none gets up her nose (nares??). I've also added the Rooster Booster Vitamin and Electrolyte supplement to their water and will keep doing so until they are not growing so quickly.
BTW. If this is the problem, the solution will be a quick and dramatic turn around and any extra vitamin B is flushed out of her system.