The ruling on a woman whose menstrual cycle is irregular

Question:
The cycle fluctuates between being seven days in the month for four years, then shifting to fifteen days for another four years. Does this happen to women?

Answer:
Allah knows best. It may happen; the cycle may change.
Q: What about what is less than this, and if the blood increases for another four years...?
The Shaykh: She must adhere to her custom and not be negligent. The Prophet (peace and blessings be upon him) commanded adhering to the custom, that she should stick to her custom. Whatever exceeds it is irregular non-menstrual bleeding; she prays and fasts, and praise be to Allah.
Q: Does she combine the two prayers if she performs the full ritual bath, or in general?
The Shaykh: She performs the full ritual bath just as Humaynah (may Allah be pleased with her) was commanded to perform the full ritual bath for the two prayers. This is a recommended practice, and the obligatory act is the ablution, but the full ritual bath is recommended.
Q: But the combining?
The Shaykh: Combining and performing the full ritual bath is better if the matter is difficult for her.
Q: Is she allowed to combine without performing the full ritual bath?
The Shaykh: The full ritual bath is better, and it is the recommended practice, but it is not obligatory. What is obligatory for her is only the full ritual bath for menstruation.
Q: But my question—may Allah reward you—is about the combining?
The Shaykh: Combining with the full ritual bath is better, and if she combines without the full ritual bath, it is valid.