What Causes Delayed Periods Despite Taking Duphaston?

What if duphaston didnt work? How can i get my menstruation back to normal? My period suddenly stop almost five months now. Doctor prescribed duphaston & i took it for 5 days waited 1 week after and still didnt grt my period. She asked me to take it again for another 3 days, its actually my 3 days today & symptom of a menstruation. Ive got my stomach scan up to my pelvis & they said its all normal the only problem they saw is i have a multiple gallstones.another doctor advised me to take rowachol for the gallstones.