83F is fine at night, but you should be near 90F in the daytime for proper digestion. For the love of everything, lose the heat rock. Get a UTH if you don't already have one, these are the best option for belly heat.
First of all, is this an adult? She could be in her brumation/ hibernation/ egg producing period. It is about that time of year for most geckos, a little past, but she could be slow if the temps are so low.
If you suspect it isn't "that time of the year" then you can try offering vanilla flavored Ensure (see any of my posts similar to this one) to jump start her appetite and make sure what goes in comes out.
Try to get a weight on her and monitor her, if she drops more than a few grams then we can step up the treatments.
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0.1 Albino Leo Gecko
0.1 Crested Gecko
1.0 Dear Boyfriend
Departed: Harvey and Spock