Is anything required of the questioner after she performed ghusl and circumambulated the Kaaba (tawaf) voluntarily in the Grand Mosque, and then a small amount of yellowish discharge (kudrah) appeared after her return home?

If you are certain of purity by the descent of the white discharge (al-qassah al-bayda') or dryness, then any brownish or yellowish discharge (kudrah or sufrah) after the end of your customary period is not considered menstruation. This is based on the statement of Umm Atiyyah: "We did not consider the brownish or yellowish discharge after purity to be anything." Your prayers and circumambulation are valid if the brownish discharge appears after them. However, if you have not seen a sign of purity, or if the brownish discharge occurs during your customary period, then it is considered menstruation.