What Causes Delayed Menstruation With Premenstrual Pain?

I have thick black/dark dark brown loose motions at least 2-4 times for about a week now.. also I missed my menstrual cycle in february which was due on 27-1st... I had pre menstrual pain however such that I though it was onse tof it.. but didn t have... I had constant cough cold chest blaockage took medicines for 2 weeks before this... what should I do.. begin a course of Deviry 10mg as said by gyanecologist back home. I have pcos and put on wieght.