Is prayer and fasting obligatory for one who suffers from an ovarian cyst, and whose menstrual period has exceeded its usual duration, while she is taking medication to dissolve the cyst?

If the duration of menstruation exceeds the usual number of days, the excess is considered menses as long as it does not exceed 15 days, which is the maximum duration for menstruation. During this extended period, prayer, fasting, and all other things that a menstruating woman abstains from must be forsaken. However, if the blood flow exceeds 15 days, the woman is considered to be in a state of istihadah (non-menstrual bleeding), and she must perform what a woman in istihadah performs.