What is the ruling for ritual purity (tahara), prayer (salat), and fasting (sawm) in the event of continuous, intermittent discharge of blood and yellowish or brownish fluid (kudra) after the menstrual period has stopped, given the unclear nature of this blood?

Your question includes four points:

First: The descent of blood in the form of spots is not considered menstruation unless it continues for a day and a night or more; otherwise, it does not prevent prayer.

Second: If blood descends at a time when menstruation is possible, it is considered menstruation, and prayer and other acts of worship are abandoned for it, unless it exceeds 15 days, in which case any excess is considered istihadah (non-menstrual vaginal bleeding).

Third: Blood that descends before its due time is considered menstruation if the minimum period of purity between two menstruations has passed since the cessation of the previous menstruation (15 days according to the majority of scholars, or 13 days according to the Hanbalis).

Fourth: Kudrah (brownish discharge) and Sufrah (yellowish discharge) during the time of menstruation are considered menstruation. During the time of purity, they are not considered menstruation. Therefore, the brownish kudrah that descended during the time of menstruation is considered menstruation and necessitates abstaining from prayer and fasting, and there is no condition to wait for explicit blood.