What is the ruling on the moisture that comes out of a woman, which has an odor and is not continuous, given her inability to determine its source, and is she required to be cautious and change her clothes for every prayer? And how can one differentiate between what reaches the joined parts (of the vagina) and what does not, and what a woman sees when she is sitting regarding vaginal secretions?

If you find moisture on your garment and cannot distinguish its source (whether from the vagina or the urethral opening), the default is to consider it pure (tahir), and we do not rule it impure unless that becomes clear.

The default is the purity of things and the validity of ablution (wudu), and one does not deviate from this default due to doubt. The principle is that certainty is not removed by doubt. So, do not pay attention to doubts about something exiting, especially if you are prone to excessive doubts, and do not inspect. Act upon the principle of purity to be safe from obsessive whispers (waswas).