Talk to General Physician on Upset Stomach

assalamualium ... im taking glucophage xr 750 mg medicine for pcos prescribed by dr ..its been 2 months taking this...last month periods came at exact date.. now my periods are 6 days late .....5th day of missed period i checked pregnancy test was negative..from last 1 week my stomach is very upset with loose motions while last 2 months loose motions did not happen...all time i felt nausea...question is is glucophage xr 750mg cause late periods? why im feeling vomiting or sickness all time?