Is what you did correct, that you performed ghusl and prayed Dhuhr and Asr after your menstrual bleeding stopped, then you ceased praying Maghrib, Isha, and Fajr after something black descended?

If what you saw was blood, then it is menstruation (hayd), and you must wait for it to stop, then perform ghusl (ritual bath) and pray. If it stops after sunrise, then the Fajr prayer is not obligatory. However, if it was a brownish discharge (kudrah) and not blood, then it is not considered menstruation, and you must perform istinja (washing after relieving oneself) and perform the prayers.