Oh, wow, I'm so sorry. I can't quite make out what type of injury this is, it almost looks like she's missing skin?
If you've already posted on the emergency forums just ignore this, but I'd definitely get some advice there right away otherwise. Let them know the brand of your medication there...
Quarantine to help ensure you don't introduce new diseases to your existing flock.
Use a "look but don't touch" setup for long enough to ensure familiarity between the groups and to limit fighting (depends on the birds' personalities, but anywhere from a week to a month would be my initial...