Huh. Maybe try putting him on newspaper or paper towels for a little while and see if the texture of the substrate is what's bothering him? It'd get you closer to finding out if this is just sensitivity or nerve damage at any rate.

The wet sphagnum moss in a hide provides at least a little microcosm of the correct humidity even if you can't keep ambient that high, since it can't really evaporate off or anything. Probably not necessary all the time, but definitely helpful during a shed.