Should I pray if I find a brownish liquid, tending towards reddishness, then turning yellow, with some murkiness when inserting a cotton swab, after a cessation of a year and a half, given that I use contraceptives and have stopped breastfeeding?

If the red discharge continues for a day and a night, then it is menstruation (hayd), and purification from it occurs when the bleeding stops, along with any yellowish or brownish discharge associated with it. However, if the duration of the blood and its associated discharges is less than a day and a night, it is not considered menstruation by the majority of scholars. If it is menstruation, prayer is foregone, and the woman performs ghusl (ritual bath) after it ceases. If it is not menstruation, and the discharges coincide with prayer time, the woman performs ablution (wudu') for each prayer, taking precautions.