I agree. I haven't treated a jaw injury, but I did have a chicken with infection/pus on her foot. It was a puncture wound that swelled up huge, and was infected. It looked like she was walking around on a large grape, and looked painful. We think she stepped on a wire or splinter or something? Anyways, whatever it was went all the way through her foot. Lance and tweezers worked the best. Yes, it was pretty gross, but it needed to be done. DH held her for me, and I cleaned it up as best as I could and got the infection out, it was quite obvious what was "chicken pus" and what was foot flesh. Then I put antibiotic cream on it and wrapped it. It took about 2 weeks for it to fully heal, and now you would never know she had the injury.
She may not want to be separated from the flock, but it will probably be the best thing. Once you've cleaned the absess as best you can, she will need time to heal away from the other kiddos. They will likely pick at her injury.
If you can, taking pictures would be nice so others can learn from it. I wish I had taken some pictures of our girl's puncture foot injury but I didn't.
I hope everything goes well for her & you!