I wanted to give you hope and to second what Ruth had to say.
Last week, we awoke to find DD silkie with crooked neck. No other previous symptoms. The other chicks and silkie of same age were fine. I thought perhaps that he/she had been injured in some way. It was tucking head under body, falling backwards, the whole gammet. I just knew it was a gonner since it was such a sudden onset. All I could promise DD was that I would try to help the chick. But that she was very ill.
We ran out got the poly vi sol, vit e, and selenium (to help with the absorbtion of the Vit E). I couldn't get my hands on prednisone. It took a week but it has been a complete turnaround so far.
We spoon fed the feed moistened with water to almost a slurry to ensure adequate hydration, scrambled eggs, vitamins. We made sure there was a heat lamp. We noticed that the chick had lost weight.
I went to the feed store for more feed and then realized that the last time I purchased feed that they had given me the WRONG feed. It was for laying hens. (Southern States feed in our area has one bag for all their feed, you have to read the paper label attached at the bottom to make sure you are getting the correct one.) I was so angry at them and at myself for not paying attention when they loaded it for me last time. I don't know if this was the cause or not but I am sure it did not help the situation.
Just continue with the vitamins, eggs, feed. I read it can take some time for a recovery, but it can happen. The chick has perked up tremendously, she would seem to go down hill at the end of the day and first thing in the morning but with some tlc she is improving and slowly getting weight back on (we hope it continues).
Keep your chin up and continue what you are doing, it can take up to 3 weeks I read in some situations.