Yes, stopping Duphaston (dydrogesterone) this month can absolutely cause this. Dydrogesterone is a progesterone hormone that helps regulate your cycle and typically dries up cervical mucus after ovulation. Without it, your estrogen levels may remain dominant longer, or your ovulation might be slightly delayed, keeping your discharge thin and stretchy even on day 21. This is a very common and temporary hormonal adjustment. Your body is simply recalibrating, which is entirely normal. If you have any concerns or experience unusual pain, please reach out to your gynecologist.