Do you have the ability to post a photo of the chick's injury? It sounds like it might need continuing care so it won't become infected and to facilitate healing.
Check out my article on healing a badly injured chick and all that it involves to get the skin to grow back in the injured area. It needs daily cleaning and constant moisture and antibiotic ointment to keep bacteria from colonizing it and killing the chick. They do live in a very germy environment.
If it's at all possible, keep the chick with its brooding mates. You can use Blue Kote to disguise the wound, let it dry, then apply the ointment and Vetericyn. Daily.
The article is linked below this post. It has photos of the healing process and what you can expect.