Talk to Gynecologist on Irregular Periods

meri sis k normally periods ate the uski shadi hogai uski 1 month me divorce hogya she was 19 use 2 month periods bilkul sahi i he divorce k bad ab 3 month me use miss hogae he uske 15 days miss hue he periods nhe i pain b he use periods ka ab kiya kare wo ta k periods uske normal hojae ajae plzz tell me bht pareshan he hum kindly plz guide us its normal or any prblm ??