Hi Mr. Jaques,
A lot of people with CH get what is referred to on here as shadows (mild but bothersome pain/headache) prior to an onset and some like myself shadow on a daily basis. Also is the headache on the same side that you had your last CH? It's hard to say if your remission is ending or if you just have some odd headache. Just incase you are going back in you might want to consider loading up on the D3 and co-factors if you do not take them on a normal basis you can find the loading instructions and list of supplements by poking around this forum. When you were diagnosed, did your PCP put you on any preventative meds or have you just been lucky and had the CH take a hike for four years? I hope you just have a strange headache!