How can a woman determine the period of her purity and when she should perform ghusl, if her menstrual cycle is disrupted and different discharges continue, such that she cannot see the usual signs of purity, knowing that waiting 15 days may not achieve the minimum purity between two menstrual periods?

The minimum period of purity between two menstrual cycles is thirteen days according to the Hanbalis. When a woman sees blood, she must consider herself menstruating. If she observes purity through dryness or a white discharge, she has become pure. The presence of white moisture does not negate purity. So, whenever she sees these moistures and the blood stops, along with any related yellowish or brownish discharge, she has become pure. Any yellowish or brownish discharge after that is not considered menstruation unless it occurs during her usual period. If the bleeding returns, it is considered menstruation as long as it is within the possible period. If the duration of the blood and what is connected to it exceeds fifteen days, or if the blood returns after less than the minimum period of purity and cannot be combined with the previous blood, it becomes clear that she is experiencing irregular bleeding (istihada).