Best bet is to take him to a vet. There area a few other threads on this forum from snakes with bumps. Some turned out to be absess from parasites much like tape worms, others are still unclear the cause of, but they were filled with pus and needed medical attention.

Take him to a qualified herp vet, and while you are there, might as well get a fecal done too. Best to make sure your new animal is clean.

BTW, the snake with the worms in the skin had clean fecals.