I would stand her in some epsom salts water and try to "draw" that thing, if there is an abcess in there. Don't let her drink the water and have it as warm as she can comfortably take. Soak at least 10-15 minutes a couple times this evening and then see how it looks. Bird pus is not like mammals, it's a really cheesy, thick goo, so it's not going to open and drain like a mammal abcess would, but it might come to the surface enough for you to tell if you need to lance the thing and clean it out..