Is continuous bleeding for three weeks, with its color tending to brownish-yellow in the last few days, considered menstrual blood that prohibits prayer, and does this necessitate a visit to the doctor?

If the duration of menstruation exceeds fifteen days, the woman is considered to be experiencing istihada (non-menstrual vaginal bleeding). She should refer to her previous custom (habitual period). If she does not have a previous custom, and she can distinguish the characteristics of menstrual blood from those of istihada blood by their signs (color, smell, thickness, thinness, and pain), then whatever possesses the characteristics of menstrual blood is considered menses, and anything else is istihada. If she has neither a custom nor the ability to distinguish, she should observe the predominant custom of women, which is six or seven days, and anything beyond that is istihada. After the period she considers menstruation has ended, she should perform ghusl (ritual bath), pray, and fast. She should perform wudu (ablution) for each prayer after its time has begun, taking precautions and binding a cloth over her private parts. It is permissible to consult a female doctor if there is a concern about an ailment.