I’m so sorry you have not received help. Unfortunately, I don’t have experience with this. Can you show us a photo of the vent itself and the wound? How is she doing? I am wondering if she has a prolapse (tissue bulging out her vent) and the flies were attracted to that. It might be good to clean her again and apply antibiotic ointment to the wound. Can you keep her inside and away from flies for a bit?