Talk to General Physician on Gynecological

plz tag dr riba baig assalamualium ... im taking glucpphage xr 750 mg 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 causing late periods? why im feeling vomiting or weakness all time?