How long has it been since she's eaten? How big is she? Since she just shed last week, that's not it. What is the temperature in her enclosure? Checking for mites, as Steve said, is a good starting point. She could have internal parasites as well, or she could just be getting ready to brumate. How long have you had her? Is she wild caught or captive born/bred? What part of the country are you in and what's your weather been like for the last couple of weeks?