try to keep his hot side temp no more than 93, it might be he just doesn't like it so hot.....you just said he's in shed, so it might just be that his vision is not very good and he is preferring to stay hidden until after the shed, im thinking he'll got back to normal after he sheds, if not he might be stressed out for some reason, check his husbandry again and play with the temps until you see that he becomes a little more active, also remember that they are nocturnal, it might just be that he comes out when you are sleeping and you just cant see him, i hope this helps =]