I always have regular cycle but recently had it oct. missed nov had it dec and im late this month jan. i don't take bcp. what could be wrong?neg ptest

See answer : There are many causes of abnormal periods and almost all woman will experience abnormal periods at some point in their lives. Reasons can vary from benign and often self-limiting causes such as stress, heavy exercise, changes in diet, illness, and travel, to meds, to more serious underlying medical conditions: uterine fibroids, endometriosis, pelvic inflammatory disease, polycystic ovary syndrome.