I've not seen anything like that before. If it were me, I would go to a professional reptile vet, and then see if they can do a poop sample on it to see if any parasites are detected.

If that snake is housed with the others, I would remove it immediately and put it into quarantine in a separate room (tub and everything disinfected before putting it back in the rack). You dont want your other snakes getting what he has.