Chick is struggling

[Birdsandsuch]

I got new birds about four weeks ago, and while most are thriving, one is struggling. She is a black austrolop, about four weeks old. She stopped growing and is about half the size of the rest of the flock. She is completely unable to stand and almost crawls around using her wings for balance. She is eating and drinking on her own but not a lot. I think it is a case of wry neck, but I am not that experienced. She is currently separated and I have been giving her vitamin e and selenium, but I can’t tell if it is working. We have been feeding her egg yolk, but I don’t know if that is helping either. Other members of my family believe she will not make it, but I am holding out hope. I am hoping for some guidance as how to help her, or if she is even worth helping.