I have one out of 5 lizards in a tank that over the last week is starting to look grim. They are fence lizards (sceloporus undulatas), similiar to an emerald swift. She has shrunk up and her sides look sunken in, the back of her legs look the same. She has a ridge on her back, im pretty sure is her spine. There is some stuck shed at the base of her tail. I have been rubbing mineral oil on her working on that. I haven't had a chance to pull her out of the tank yet. Her 4 tank mates are doing fine. Could this be some kind of full body stuck shed? It's not obvious other than that one spot. She still seems active. I have not seen her eat but have seen her pursuing crickets. She drinks. Working on pics.
https://i.imgur.com/XOEdqiI.jpg