What is the ruling regarding the fasting and prayer of a woman who experienced menstrual bleeding for a full month, then took medication to prevent menstruation, then the bleeding returned during Ramadan, and she cannot distinguish whether it is menstruation or istihadah, and she does not have a known regular cycle?

If the blood returns to a woman less than thirteen days after its cessation, and the duration of the blood exceeds fifteen days, then she is a mustahadah (experiencing irregular bleeding). Given that she has no known regular period and is unable to distinguish (between menstrual and irregular blood), she should observe six or seven days each month as menstruation, following the custom of the women of her family. Then she should perform ghusl (ritual bath) and consider anything beyond that as istihada (irregular bleeding). She should refrain from fasting and praying during the days counted as menstruation. After performing ghusl, her status during the days of istihada is that of ritahiraat (ritually pure women), so she should fast and pray, taking precautions and performing wudu' (ablution) for each prayer after its time has begun.

However, if the blood remains absent for thirteen days or more, then the returning blood is considered menstruation. She should wait until it ceases, provided it is less than fifteen days, then perform ghusl and pray. If its duration exceeds fifteen days, she is a mustahadah, and she should do what has been mentioned and make up the prayers missed during the days exceeding the menstrual period.