How old is your son? I have had episodic CH since I was 16, and I am now 33. I remember in my younger days I would often skip my fall cycle all together. Not sure why?? However, in my late 20's the cycles became much more consistent with both a fall and spring one. I sometimes will still have the fall cycle start early or late, but the spring one is like clockwork. That probably doesn't answer your question, but I would say it is absolutely normal to skip a cycle especially if he is younger. Hope it doesn't start for him this fall and if there is any chance it is the sunflower seeds tell him to eat more!!!