Hello, this is Dr. Linda. I hope I can help with your question today.
If your little hen is eating well, then you probably do not have to have her seen by a veterinarian. If she is eating, but not well, supplement her with some cooked egg, corn bread, pancakes, bits of melon & greens such as spinach & kale. I will guess that the spray you are using is vetricyn, which is very good for wounds.
You have been introduced to the world of tiny dinosaurs. Chickens can be vicious, cannibalistic, eating machines. They are incensed by the sight of blood, & even newly hatched chicks will attacked another newborn if they see red. It is the reason most people will use a red brooder lamp, not just for the heat, but to disguise & protect any injured chicks. Chickens can not see blood with the red light. Once your hen has more or less healed ( all the feathers do not have to grow back ), you can place her back in with the rest of the hens. Supervise closely for the first day or so to make sure she is not picked on again. Chickens have pretty good memories. Hopefully as she matures, she will find her place with the rest of the hens, but it is amazing how much like high school it is within a flock.
I hope this makes sense & you find the information useful. Please let me know if you have any further questions or concerns.