It is very common to experience a delay in your period after stopping Duphaston (dydrogesterone). Typically, a withdrawal bleed starts within 2 to 10 days after your last dose, but it can sometimes take up to two weeks. The cramping, breast tenderness, and back pain you are experiencing are actually classic signs that your body is preparing for your period as your hormone levels shift. Since your pregnancy test is negative, you can take a deep breath and give your body a few more days to adjust. If your period does not start within 14 days of stopping the medication, please reach out to your doctor for a gentle check-in.