What is the ruling on making up the prayers a woman missed during her irregular bleeding due to her ignorance? And what is the maximum duration for menstruation?

If a woman is certain that she missed prayers during days of istihadah (post-menstrual bleeding), she must make up those prayers, and they are not waived merely due to ignorance of the ruling. The maximum duration for menstruation, according to the majority of scholars, is fifteen days. Any bleeding beyond that is considered istihadah. If she becomes pure after fifteen days and bleeding returns before the passage of another fifteen days, the returning blood is considered istihadah, not menstruation, because the minimum period of purity between two menstrual cycles, according to the majority, is fifteen days.