What is the ruling of Islamic law regarding the fasting of a woman with an irregular menstrual cycle if her period starts two days before Ramadan, knowing that it had only started two weeks prior?

If the bleeding returns after fifteen days from the cessation of the first, it is a second menstruation. If it returns before this period, then the first bleeding, along with the period of purity within it, and the second bleeding are counted. If their total duration is less than fifteen days, then the second bleeding is a continuation of the first menstruation. This is the view of the Shafi'is. As for the Malikis, they do not count the intervening period of purity as part of the menstruation. They consider the two bleedings as one menstruation if their total does not exceed fifteen days or the usual period plus three days. If the total of the two bleedings or the combined days of bleeding exceed fifteen days or the usual period with an increase, then the woman is considered to be in a state of istihadah (non-menstrual bleeding).