i was due my period on the 24th aug and it didnt arrive untill the 29th it lasted 1 day, i am very tierd,get a dull ache down below have sore nipples and get cramps in my legs. i am due my period again today and it hasnt arrived my last full period was on the 24th july and lasted 4 days i am normally regular and consistant every month since i was 11 years old. what can this be?