As far as what to treat it with, you'll need to be able to properly evaluate the wound first. I've heard chickens are great at "walling off" areas of infection, meaning the infection stays localized and does not go systemic. In that case, a local treatment can be just fine. Antibiotic ointment, etc. A lot of times, just cleansing the wound well and keeping it clean can do the trick. they have wonderful immune systems and powers of recovery.
Once you get it clean, you'll need to focus on keeping her hydrated and properly nourished. Wounds, especially those that make pus or seep, take a lot or liquid. She'll need a lot of water to replace that. You might look for a home made electrolyte solution or buy some Save a Chick to help her along. And she'll need an increase in protein for healing, all those amino acid building blocks come from protein. Egg is fine, bits of meat, some folks use cat food, etc.