What should a woman do about making up prayers after she learned that the brown discharge that preceded the red menstrual blood was not menstruation, and she does not remember the number of days this discharge continued?

Scholars have differed regarding the ruling on yellowish and brownish discharges, and the preferred view is that they are considered menses if they occur within the customary period or are connected to the blood at its end. So, if the brownish discharges occur during the customary period, they are menses, and one must abstain from prayer. However, if they occur outside the customary period, it is obligatory to perform prayer until the sight of menstrual blood. If you wish to make up for missed prayers, then make up what you predominantly believe will absolve your responsibility. According to the majority of scholars, there is no making up if the discharges occur at a time when they could be menses.