Must a woman make up for a day of fasting if she finds menstrual blood—of a brownish color—after breaking her fast in Ramadan, and she is unsure if it appeared before or after the Maghrib call to prayer?

The brownish discharge is a turbid discharge [kudrah] and is considered menses if it appears during the usual time of menstruation. The fast is valid if there is doubt about its appearance before or after breaking the fast, because it is not considered to exist legally except at the time it is observed. For a [ritual] impurity [hadath] is attributed to its closest possible time.