....check your journal...you know, the one you keep on when, where, how hard, how long, activities, eats, stress, weather, etc..... soes you (and maybe a good doc) can figure this out (and then stop journaling)....cuz it sounds like maybe there's "something" happening one day but not the next (like weekend headaches from no caffeine)....we call 'em "triggers"...
....another thought......if yur fairly new to CH it could be your "pattern" has not settled in yet...for some it takes a while (1 yr for me)................