Is it permissible to fast and pray while red menstrual blood continues to flow, after it had been brown and scant, knowing that the menstrual period does not exceed five days?

The maximum duration of menstruation according to the majority of scholars is fifteen days. As long as the blood does not exceed this period, it is considered menstruation, which prohibits prayer and fasting. Your fasting in Ramadan while bleeding was a mistake, and you are obliged to make up for those days. If the blood flow exceeds fifteen days, then you are experiencing istiḥāḍah (non-menstrual bleeding), and you should act as a woman experiencing istiḥāḍah by referring to your usual period, or by distinguishing the blood, or by the common custom of women. As for brownish discharges (al-kudrah and aṣ-ṣufrah), they are considered menstruation during the accustomed period, but not outside of it.