Bleeding More Than One’s Set Number of Days

If a woman has more than her set number of days of bleeding (aadat), but the bleeding does not go beyond 10 days, then all will be haidh provided that she was clean after that for at least 15 days.

If she was not clean for 15 days or more then she will fall back onto her aadat.

Example: Her aadat is the first 5 days of every month, but she went through 6 days of bleeding.

The 6^th day is also haidh.

But if she was clean thereafter for only 14 days and then saw some blood, she stays with her aadat, and the 6^th day is istihaadhah.

(Manhalul Waarideen)