Hi welcome to HCM.... You are having irregular menstruation complaint mainly ... So for getting regular period and to avoid pain during menstruation progesterone group drug can be used ... Primolut n is norethisterone group of drug... It is usually given after ovulation and with stoppage of medication within three to four days menstrual bleeding occurs ... So follow doctor advise and complete course of tablet ... If still such problem remain than complete hormonal profile , tsh estimation , pelvic examination and USG done for further work up... Take care Advise : Follow up gynecologist consultation