First, those thermometers you're using aren't very accurate (can be 10C+ wrong) so those temperatures are likely to be wrong - not your fault, shops just insist on selling them. Invest in some digital thermometers, can be picked up cheap from ebay, these will give a more accurate measure of your temperatures.
How long have you had her? She could still just be settling in and getting used to her new surroundings. It's completely normal and can be around 2 weeks before they settle. Keep trying with the veg and live food - when she's hungry she'll go for it.
Can you describe the rest of your setup in case something else might be affecting her? Things like UV light %, brand and age is helpful, as well as any other supplements.
Edit - they often turn black when they're cold, confused, nervous, annoyed etc. Nothing really to worry about. What do you do with your heating at night? And what is your heat source?