If she does not have a time when she knows she is taahir, she should insert a piece of cotton or something similar, and if it comes out clean, she should fast, and if she starts to bleed again, she should stop fasting, whether the blood is a flow or just spotting, because it breaks the fast as long as it comes at the time of the period. (Fataawa al-Lajnah al-Daa??imah, 10/154).