It's probably a side effect of the extreme malnutrition and dehydration that he is suffering because he is not being seen by a vet to address whatever is causing him to lose him appetite.
This gecko is very sick. He deserves medical care. Stop dinking around on the internet and GO TAKE HIM.
We are as gods to the beasts of the fields. We order the time o' their birth and the time o' their death. Between times, we ha' a duty. - Terry Pratchett.
"Men have forgotten this truth", said the fox, "But you must not forget it. You become responsible, forever, for what you have tamed. - Antoine de Saint-Exupéry