My leopard Gecko is always cold?

Question
I have an adult female leopard gecko, I haven't had her very long she was given to me by a friend. And when I got Dottie, she would eat regularly and use her heated area to get warm. But lately, she hasn't eaten anything, and is no longer using her area where her heating pad is located. I assumed that her eating habit had changed since it is now winter and could be going through brumation? She's been hiding inside a stone cave where it is cooler, and when ever i pick her up she is always cold.

I have a 10 gallon tank and use a red reptile light day and night that distributes 60 watts. Her floor thermometers read 85-90F during the day on the hot side and 70-75F at night on the hot side. On the cold side, the other floor thermometer reads an average of 30F.

I cannot figure out why she won't use her heating source anymore. Or why she's not eating. Her tail prior to the temperatures dropping due to winter was fat and now it's starting to look as if it's shrinking since it's getting more wrinkled and not as "plump." She just stays hidden most of the time, unless I take her out. But I'm afraid if she continues to stay cold she could get deathly ill and die, and I really don't want that to happen. Please help me what should i do?

Answer
Hello Tiffany,

They can go through minor slow downs due to the seasons, etc.  
Since she is not willing to stay on the warmer side, you may need to heat more of the tank.
You can use an undertank heater or the heating pad.  The 88-90 temperatures are fine.  Do you leave the heating pad on 24/7, or do you use the heat bulb for nighttime?
Have you done a fecal on her to see if she may have worms/parasites?  That is a possibility as it will also make them lose their appetite.
Are you using sand, tiles or paper towels for her?
What foods have you fed Dottie previously?  Do you offer calcium for her several times per day also?

Do you have any pictures of her?
If she is losing weight, you can get some chicken or turkey baby food to feed to her with a plastic dropper or syringe, several times per week to help.

Let me know how she is doing.
Tracie