X2
Let's take it a step further.
Can you post some photos of where they are currently housed?
Do you have their outdoor housing ready?
Where are you located?
It looks like the chick has been picked on severely. Separating her so she can heal was a good idea. Flush the wounds with saline and apply some triple antibiotic ointment or Vetericyn.
Watch to see that she is staying hydrated well and eating. You can add some poultry vitamins to her water to help with the healing process as well.
More than likely not enough space, possibly too much heat and boredom is the cause.Try to get them outside where they have plenty of room as soon as you can. For this little, she will have a hard time being integrated if you keep her separated until she completely heals - so placing her cage or kennel next to the others will be beneficial. If the spaces of the kennel are quite large where the others can reach in an peck at her, you may need to consider covering it with wire. In a few days, once she has scabbed over help hide the wounds by applying some Blu Kote, then put your ointment on top. If she goes outside, be mindful of flies lighting on the wounds as well.