Are the dark brown secretions streaked with blood considered menstruation if they occur 12 days after the end of the previous menstrual period?

This returning blood is not considered menstruation due to the absence of a sufficient interval between the two menstrual periods and because the total amount of blood exceeded the maximum duration of menstruation. Accordingly, this blood is considered irregular bleeding (istihada), and you must clean yourself (istinja') and perform ablution (wudu') for every prayer after its time has begun, and pray with your ablution as much as you wish until the time for that prayer expires. Nothing is considered menstruation except what aligns with your regular period, or by discerning the valid characteristic (of menstrual blood), and then, by the predominant custom of women.