If there is what sounds like head flinging, maybe it is neurological and maybe some vitamins in water would be good for her, especially if others are keeping her from food. If it was sudden onset, the chick could have gotten a bad hit to the head and sustained a bit of damage, in which you'd want to make sure she keeps eating and drinking, as they can recover from them at a young age. I would avoid treating with antibiotics if you don't know if it is a bacteria infection, such as animal bite or injury. Else you'd just increase the risk of the antibacterial not working when you really need it. They are essentially poisons which kill microbes, and you generally want to avoid incubating the eggs because it may increase the risk of developmental defects, thus deformed chicks.