Hi Megan, Someone who worked at Sydney Aquarium brought me a turtle many years ago that had an identical problem. I took the turtle and dug through the skin and found that the bone eating, anaerobic bacteria had eaten through the skull and the brain was exposed. It took 3 months of rehabilitation but the turtle survived and the skin eventually grew over the wound. If it is what I think it is then it will need to be opened up and the dead tissue and cheese like, granular pus removed ASAP as the bacteria will not stop unless it is removed. A course of antibiotics will not stop this bacteria by itself. I'm really sorry for giving you this horrible diagnosis, but it is in the early stages if it indeed is the aggressive bacteria I think it is. Once again I apologise for the bad news, but at least it's in the early stages and can be stopped.