If he is comfortable sitting on your hand, try taking him outside in the sun. Just sit there for a bit and let him bask. The natural sunlight seems to get my chameleons system moving.
He may not have wandered too far. Keep looking in plants/trees (sometimes they like to get up high as well), see if your neighbors will let you look in their yards. Depending what birds/animals are around where you live he may have been taken by something.
If you find him, don't leave him...
I agree with the live plant (pothos and schefflera are good options).
Also I would double check what you are using to measure the humidity with and maybe compare it with something else. With a glass cage and fogger going that seems low.