How did she get this wound?
There are a couple things you can do. The first thing I would do is apply Blu-kote to this wound. You can get this at any feed store in the horse section. It is a spray that helps to stop infection.(wear gloves with this stuff as it stains your hands and clothing.) I would spray this area once or twice a day for a couple weeks. If you do not have any blu-kote right now, I would apply some neosporin or some triple antibacterial ointment. It shouldn't have the pain killer in it, but if that is all you have, I would go ahead and use it this time only. (the pain killer is not good for chickens) But tomorrow if you can get some blu-kote, this would be better. Keep her separated and in a dry clean area until this wound grows harder skin on it. If this is something that is exposed and other birds can see it, you will need to continue spraying it just to hide this area so the others can not pick at it. But for at least for a few days, keep her separated, in a clean area and dry. Apply some sort of antibacterial meds to this area. You might also for one time only, pour some peroxide on it. But only once. It can destroy heathy tissue as well, but is good to use the first time to kill off bacteria. If this wound came from something that caused truama to her, she maybe cold. Feel her feet. If they are cold, then so is she. Get her under some heat for tonight if she is cold so she doesn't go into shock.