The first time you get some pus out, you will know what is and isn't. Sometimes you can feel it in there, it's harder than the healthy tissue feels. It is not my favorite thing to do, but the sooner it's taken care of the better. The worse it gets the worse it is to clean out and the longer it takes to heal. Give yourself a block of time, take your time, and stop and take a moment to breathe if necessary. If it bleeds just use paper towels or gauze and put pressure on it til it stops and you can continue. If you have someone to help, all the better, but I have done this by myself many times. If you lay her on her back wrapped in a towel and put a small cloth over her head, they usually lay pretty still. A vet that sees birds will do it for you if you have access to one and the cost is an option for you.