Must one fast if menstruation has ended and a brownish discharge appeared after performing ghusl, and before or after the Fajr call to prayer, with uncertainty about the exact time of its appearance?

A woman identifies purity by one of two signs: dryness or the white discharge. Yellowish and brownish discharges connected to blood are considered menstruation. Therefore, you are still menstruating, so do not fast or pray until you see the white discharge or dryness.