I would go and get some Blukote. It did amazing things for my 4 that got hurt 3 weeks ago. They had bad and I mean bad deep gaping wounds. Flush with saline, I wouldn't use the peroxide mainly because it kills most everything it touches and you want the new skin to come in and some bacteria is necessary. Spray the Blukote on the wound. I'm totally sold on that stuff. All my girls have survived and are healing beautifully. This is the thread, maybe you will get some help from this.
https://www.backyardchickens.com/forum/viewtopic.php?id=15537
https://www.backyardchickens.com/forum/viewtopic.php?id=15537