Poor Scrappy. It is difficult to see details as the picture is blurry. It almost looks like a mass in the picture. I would make she isn't licking or scratching it. I would put a cone collar on her to prevent the licking if needed. I would also have your vet take a look at it. With how red and ulcerated it is, she likely needs some antibiotics and may need to have it removed. I hope this helps.