either physically give him a bath or provide a deep enough dish in his tank that he can soak himself, he should use it if he needs it. they don't shed in one piece like snakes, they tend to flake off in pieces.
maybe if you can get a decent picture, it would help,
i have pygmys and they have patches that seem a little stubborn at times, but they have a 'pool' if they need it, i haven't needed to intervene yet,