Determining the menstrual period duration when menstrual flow color changes and repeats irregularly?

Primary text

If a woman observes five days of black flow, followed by continuous red flow, and this pattern repeats in the second month, then in the third month the entire flow becomes red. In the fourth month, she sees a pattern like the first, and in the fifth month, she sees five days of red flow, which then turns black and becomes continuous, her menstrual period is defined by the black flow observed in the first, second, and fourth months.