Poly vi sol is a suggestion that is supposed to be IF people already have it on hand for their kids and NOT for them to go get it. Also they may be treating for a vitamin deficit. I don't give extra for a simple injury... but it won't hurt IF you WANT to give some vitamins short term. Most important is that water stays poo free and they are fed a formulated starter or flock raiser.
Poultry nutri drench is a better product for chickens, but likely isn't needed now. It's always good to get it and have on hand though.
I would put the chick back with the others as long as it isn't being trampled and can get to food and water. Being alone or separated can be stressful.
Yes, your chick will very likely be OK. It can take a short period of time to recover from a twisted ankle or knee type injury, or pulled muscle, or maybe even bruised bone. Accidents stink.
Hope your babe is up and around quickly!
