What is the ruling on fasting the days during which menstrual bleeding stopped and then resumed, and is it obligatory to make up the days that were fasted during the period of cessation?

If the menstrual bleeding stops completely before the usual period, and there are signs of purity, then ghusl (ritual bath), prayer, and fasting become obligatory. If the blood returns before fifteen days have passed, this is considered part of the first menstruation, and prayer and fasting must be refrained from, unless the total days of bleeding exceed fifteen days, otherwise, it is istihada (non-menstrual bleeding). However, if the blood returns after fifteen days or more, it is a new menstruation. Consequently, there is no make-up for the two days that were fasted during purity, while on the day the blood returned, prayer and fasting are not permissible. If one fasts on that day, the fast is invalid and must be made up for.