hi. ive been working with skinks for quite some time and have had similar issues before . but i think since he is so old and being suddenly moved into a smaller cage caused a lot of trauma to the lizard. and stress or trauma can most likely kill a skink. for now keep him in whatever cage his in put in a little towel for him to curl up, keep him hydrated, and try your best not handle him and make sure hes kept well heated in an area with not much noise. hope i helped and i wish your little guy luck! reptilelover100 p.s make sure the towel is the only thing in his cage besides water!!