Eventually, you will have to put this chick back with the flock. When you do, the chick, whatever age she is at the time, may still be bullied by the hen. If the hen really doesn't like the chick, the hen may eventually kill the chick. I have seen this in my own flock and it can get pretty ugly.
Unless you plan on making her a house chicken. I would put the poor baby out of her pain and suffering, instead of prolonging it, just to see.
Sadly this is part of keeping chickens, that's why they call it animal husbandry, because we are responsible for those animals' care. And sometimes we have to do hard things.
Just my humble opinion, based my experience
Good luck with whatever you decide
Unless you plan on making her a house chicken. I would put the poor baby out of her pain and suffering, instead of prolonging it, just to see.
Sadly this is part of keeping chickens, that's why they call it animal husbandry, because we are responsible for those animals' care. And sometimes we have to do hard things.
Just my humble opinion, based my experience
Good luck with whatever you decide