Chick attacked, now won't walk

[ChickenTendinBoyMama]

I had a chick disappear from free ranging with Mom. 24hrs later it appeared on its own outside the run. Had injuries but it was standing, chirping, eager to eat and drink. Its wounds seemed to had already sort of scabbed over/dried by then(the pictures attached are already from 2 days after found)
The issue now is since the morning after it came back and I've had it indoors with me it's not wanting to stand/walk anymore. It makes its way to food and water but is too wobbly to stand.
Is there a vitamin deficiency now that I need to be treating due to injuries?

 

[azygous]

You do not mention treating the wounds. Wounds not washed with soap and water to remove bacteria but instead allowed to scab over without treatment trap bacteria under the scabs. That bacteria then multiplies and causes serious infection that can kill tissue and spread into the blood stream, sickening and then killing the chicken.

You should first treat for shock, even though it's been a while since the attack. Severe untreated wounds alone cause shock. Mix one teaspoon sugar in one cup water with a pinch of salt and baking soda and give to the chick to drink. Dip the beak to get it started. Syringe it into the chick if the chick is too weak to drink. See the photo below.

Next, you must debride the wounds to get rid of accumulated bacteria. That involves using a wash cloth on the wounds to remove the scabs and all dirt and bacteria. To soften the scabs for easier removal, coat them with undiluted Dawn detergent, let sit to soften the scabs, then use the wash cloth to gently scrub the now jellied scabs away.

Dry and coat all wounds with triple antibiotic ointment. Do the washing and debriding every day to remove bacteria and nonviable skin cells and keep the wounds coated with the ointment so they don't dry out. you do not want scabs to form as they trap and grow bacteria and retard growth of new skin.