Suggest A Medication To Induce Menstruation

Hi, I have been given a course of 5mg tablets (3 per day for 1 week) to induce a bleed, however the pharmacist said she had never seen this used for that purpose before so I am concerned that it will not work. If it does when should the bleed occur, during or after the course?. For info, I am trying to get pregnant and need a bleed to have a hysterosalpingogram to check my tubes. Please help, many thanks, Tara