What is the ruling on Tawaf and Sa'i if a woman suspects the discharge of fluids during Sa'i, after Tawaf, and cannot be certain whether it is menstrual blood or not?

A woman becomes pure from menstruation upon seeing the white discharge or dryness. What descends after that, such as a brownish discharge (kudrah), a yellowish discharge (sufrah), or even blood, does not harm her, because it is not considered menstruation as long as it occurs after purity.

Therefore, if your wife became pure and then saw these discharges during the Sa'i, then her Tawaf, Sa'i, and Hajj are valid. This is because purity is a condition only for Tawaf, and she performed Tawaf while pure.