Red spot on Rinzler’s lower lip?

[ReptiFiles]

It's a little difficult to tell from the picture, but it looks like a minor abrasion to me — it should clear up on its own. However if you start to notice redness and/or swelling, it would be worth taking him to the vet for an examination.

Since Rinzler is an Indonesian, his humidity needs to be at 60-80% for best health. The easiest way to facilitate this, I've found, is to mix water into the substrate until it is uniformly moist (but not wet).

[ReptiFiles]

36x18x18 is the bare minimum for a blue tongue skink. I'm sure he wouldn't object if you upgraded him to 48x24x18 or larger.