Somersaulting chick. Could very well be retained yolk sac, if so..not much you can do.
Could be a vitamin deficiency ( due to several possible reasons ). If it's from a retained yolk sac then sadly, again, not much you can do short of surgery by a qualified vet , that would be costly and quite possibly of no help in the long run.
Try this...get some vitamin E IN THE BIRD .
Take a gel cap and puncture it with something clean and sharp then squirt it in the chicks mouth , give it some time and see what happens.
May have to do this 1 x a day for 2-5 days before you see if it helps any .
Make sure it has plenty of warmth, fresh air and sunshine, fresh clean water and ROOM TO EXCERCISE ...this means for ALL of your chicks...ALWAYS !
Lack of exercise, fresh air and sunshine can cause many problems in chicks and this "could be" one of the problems from not having those
but good chance it's from a retained yolk sac.
If it's warm enough for YOU to be outside barefoot then that chick can /should be outside also while it is warm enough.
Good luck, hope you can pull it out of this but if not at least you know what to do for the other chicks to help prevent it.
Also, add a good vitamin/ electrolyte/ probiotics supplement in the water and/or feed for ALL your chicks .... especially get some in that one ASAP.
Do this for several weeks....Rooster Booster makes a good one that can be bought at
Tractor supply, comes in a little 8 oz. white plastic jar with a yellow label.