to check for mites, but hell I have seen first hand in the past season what those dang things are capable of and how the lizard acts when they are present. Everything you say I have seen. Even the first day he arrived and you said he had some old wounds/ sores and things.
Hey I don't claim I know for sure, but I certainly have my suspicions. They are so tiny you would not see them, do the oil thing on the tummy and keep looking with a magnifying glass for any tiny specks to appear. Tell your vet to do a check with oil if you can't.
The collared you have comes from the same region I got a group from and they were loaded. Do You have a magnifying glass??
The reason they are a bit active when arriving (wc collareds) is they were in a large area IF they had mites they are not as bothered as they don't stay in the same place long.
*** BUT.... when we catch them and put them in a small tank they now are in the same spot and with the mites they came with plus whatever mites / eggs have hatched in your cage.
We immediately think... hmmm .... wild caught, they are just failing to survive in captivity , not eating, not basking, lethargic, and they are indeed NOT thiving because something is ZAPPING their energy.
I hope I'm wrong, but PLEASE check and check good. And this is something everyone can remember no matter what the findings are.
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PHEve / Eve