Suggest Treatment For A Delayed Menstrual Period

hello doctor,i am a 21yr old woman..last month i missed my periods and in da month of January i menstruated twice 1st was @ da begining of da month and 2nd tym @ da end of the month..i always use protection while having intercourse & as i was worried so yesterday i tuk 1 preg colour card test & it was negative..i have polycystic ovary and my menstrual cycle is irregular..so as per doctor's prescription i tuk Modus 10 for 7days and now its 2days after havin da tablet dat i dint start menstruating....please sugest something....