Is the brownish discharge that preceded menstruation considered menstruation, and what are the implications of that concerning Umrah and exiting Ihram, and is expiation obligatory?

Spotting (al-kudrah) is not considered menstruation unless it occurs during the usual time of menses or is connected to blood. So, if spotting occurs outside the accustomed time of menstruation and is not accompanied by menstrual pains, then the Umrah is valid. However, if it occurs during the accustomed time of menstruation, then the Umrah is invalid according to the majority of scholars due to the invalidity of circumambulating (Tawaf) without purity.

According to the majority of scholars, if the spotting is considered menstruation, then one must refrain from the prohibitions of ihram and return to Makkah to perform a valid Tawaf, Say, and taqseer. Any destructive prohibitions (like cutting hair) that were committed necessitate a fidyah (expiation), while luxurious prohibitions (like perfume) entail nothing for someone who was ignorant. Sexual intercourse committed out of ignorance does not invalidate the Umrah.

As for the Hanafi school and some Hanbalis (though this is a less preferred opinion), purity is not a condition for Tawaf, and the Umrah is valid, but it necessitates a dam (a sheep to be slaughtered in Makkah and distributed to the poor).