Is Umrah valid if brownish discharge occurred during Ihram and after purification from menstruation, and what is required of someone whose Umrah was invalid?

All praise is due to Allah, and prayers and peace be upon the Messenger of Allah, and upon his family and companions. To proceed:

The brownish drops you saw after the end of your usual period and after seeing the sign of purity from menstruation are not considered menstruation. Yellowish and brownish discharges are considered menstruation if they occur during the habitual period or are connected to blood. What you did by performing ritual purification (ghusl) after these drops and making ablution (wudu') was what was obligatory upon you, and your Umrah is valid, and nothing is required of you concerning it. And Allah knows best.