What is the ruling on prayer and purification when there is a small amount of blood, suspected to have come from the anus, and the time of its occurrence is unknown?

The presence of a drop of blood after ablution (Wudu') does not affect its validity, unless it is confirmed that it exited from one of the two private parts. This is because the ablution is a certainty, and certainty is not dispelled by doubt. The question contains a contradiction regarding the time of discovering the blood, which makes the answer unclear. If the impurity was seen and washed off before the prayer, there is no issue. However, if it was seen after the prayer without prior knowledge of its presence, the fatwa we follow is that the prayer is valid and does not need to be made up (Qada'), especially if the blood is minimal, as it is excused in prayer.