Is the blood that came down after using medical suppositories after postpartum considered menstruation or Istihada, knowing that the cycle was not regular previously and that the questioner is using birth control?

The blood that appeared on the forty-seventh day is not considered menses by the majority of scholars, because its duration is less than one day and one night, and the minimum duration for menses is one day and one night. Therefore, ghusl is not obligatory for this slight bleeding.