What should one do who suffers from frequent soiling of their underwear with feces, which causes them distress and excessive need for cleaning and changing?

If the impurity exits only during answering the call of nature, then it must be removed and the place thoroughly purified; because prayer with the presence of impurity is not valid if its removal is possible. However, if it is continuous and difficult to guard against ( سلس - سلس البول or سلس الغائط), then one must perform istinja (washing the private parts), tie a cloth over the area, and perform wudu (ablution) for each obligatory prayer after its time has begun, and whatever exits thereafter does not matter. And if it exits at intermittent intervals, then prayer must be delayed until the times it stops, even if it means missing congregational prayer, unless there is a fear of the time expiring.