What Causes Delayed Periods Along With Dark Coloured Bowels?

Missed period and black diarrhea? My period is a week late usually it s 2 or 3 days late at the most...and yesterday I had an upset stomach, nausea and diarrhea but until today the nausea and upset stomach is gone but now have black or very very dark green diarrhea I m really worried.should I be worried or will it pass?