Yikes, that's pretty significant ! Poor girl, are there any other reptile vets that could see her before then ? At least it doesn't hurt her yet. It may be some type of abscess ,[ possibly from a cricket bite like Karrie mentioned ] a vet should be able to take care of that but the sooner the better. It could also have been rubbed raw on the tile and some bacteria got in it. If it IS broken, she sure is being a tough girl walking on it. To give her a softer flooring you can use waddded up newspaper or some old towels. Best wishes !