Hi, congratulations on the plunge into lizards, they are awesome creatures! I would have to say parasites seem to be high on the list of what may be the problem. You may want to have a fecal done. Or use some panacur if you can't get to a Vet.

But in the mean time, check for mites, skinks have those big scales that mites like. Maybe try some oil and see if ya spot any.

I hope you can get them to perk up and all be be fine. Let us know how ya make out, maybe post a couple pics for us!
Suncharmers kids

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PHEve / Eve