Hello, I have gone through your query and understood the concern. Since the menstrual pattern in the current cycle is a deviation from your normal in addition to your symptoms of frequent micturition and headaches, I suggest that you test for pregnancy through the estimation of the serum beta-hCG titres. If negative, which is more likely in view of your regularity in consuming the pill, the next possible cause is a urinary tract infection which should be excluded through urinalysis. A trans-vaginal/pelvic sonogram is also needed to know the status of the pelvic organs and exclude any cysts. Hope this helps.