Is it permissible for me to fast the days exceeding my usual menstrual period (five or seven days), which increased due to illness and taking progesterone medication?

The maximum duration of menstruation, according to the majority of scholars, is fifteen days and nights. If your accustomed period extends beyond five days and becomes seven, then the excess is considered menstruation. If it extends beyond seven and becomes nine, then the excess is also considered menstruation, as long as the total duration during which you experience blood and its accompanying signs does not exceed fifteen days. Therefore, you should not fast these additional days that have extended your menstrual period; rather, you should consider them menstruation, abstain from fasting and prayer during them, and make up for their fast after Ramadan.