What is his gram weight now? 100g is kind of significant but isn't really that much over all. As long as he is drinking, he should be okay.

Does he have two hides? Maybe you could try different hides or put lots of crumpled newspaper in the tub with him?

Aslo, maybe raise his temps by a degree or two and see if that tricks him out of thinking its breeding season.

Just a few suggestions. . .