Is it permissible for a woman to wait a full day to ensure the complete cessation of menstrual bleeding, especially if a small amount of blood appears after the cessation of the initial bleeding and the discharge of brownish fluid? And is her ablution invalidated if she lifts the tissue to check and fluid is discharged?

The whitish-yellowish discharges are not considered yellowish (ṣufra). During her menstrual period, a woman may wait for a day or half a day after seeing the sign of purity (dryness) to ensure the complete cessation of blood flow, because it is characteristic for blood to stop and then flow again. This is the view of Ibn Qudamah. We advise the questioner to stop scrutinizing and verifying to avoid falling into waswasa (obsessive whispering), and performing ablution at the time of prayer is sufficient for both obligatory and supererogatory prayers. We also advise her to supplicate, humble herself before Allah, and consult a psychiatrist.