Is it permissible for a girl to pray when a heavy bleeding, resembling menstrual blood, flows from her at an unknown time outside of her regular menstrual cycle, due to an unknown cause?

If the bleeding occurs at a time when it can be considered menstruation, meaning that the interval between it and the previous menstruation is the minimum period of purity (thirteen days according to the Hanbalis, and fifteen days according to the majority of scholars), then it is menstruation and all its rulings apply. However, if it occurs at a time when it cannot be considered menstruation, such as when the interval is less than the minimum period of purity, and the total of the two bleeding periods and the purity in between them exceeds fifteen days (the maximum duration of menstruation), then it is istihadah (non-menstrual vaginal bleeding). In this case, the woman must take precautions, perform ablution for every prayer after the time for it has begun, and she has all the rulings of pure women.