[cypher]

The scratching may have been from the bugs, it's hard to say without knowing what they are.
He's probably stressed by the cage clean too & it will take a while for him to settle again.
I would keep an eye on him for now, if he continues to keep scratching then I would contact your vet.
You could also give him some extra flax seeds & a drop of evening primrose a day to help his skin & coat recover, used together they can really help but you would still need to contact the vet if there is an ongoing underlying problem.