What is the ruling on the fasting and prayer of a woman who doubts her purity from menstruation? Is she required to make up the days she fasted while in doubt about her purity?

A woman with irregular bleeding (Mustahadah) whose blood flow is continuous should rely on differentiation (between menstrual and non-menstrual blood). If she cannot differentiate, then she should rely on her customary period. It is not permissible for a menstruating woman to fast or pray until she is certain of her purity. If she does so knowingly, she commits a sin. If she does so out of ignorance, we hope she will not be sinful. In any case, she must make up any fasts she observed during her menstrual period.