S.G.
Is there something different he's started eating or drinking before going to bed. Foods can trigger bad dreams. I can't eat Braum's chocolate ice cream before bed because it gives me nightmares. (bummer...) My 5 year old nephew also had problems with nightmares. This may sound odd but my sister got him a real Indian dream catcher & now he doesn't have nightmares. They shake it out (outside) every once in awhile, to get rid of the bad dreams. It may sound like vodo, but it's really worked for him. Good luck!