Praise be to Allah.
The way to know whether a woman has become pure from menses is through one of two signs: emission of the white discharge, or dryness and complete cessation of bleeding. In that case she should pray and fast, then if the bleeding resumes, it comes under the rulings on menses, and she is not regarded as mustahaadah [experiencing non-menstrual bleeding) unless the bleeding is continuous, or it only stops briefly. This is according to a fatwa of Shaykh Ibn ‘Uthaymeen (may Allah have mercy on him) in Fataawa al-Mar’ah al-Muslimah (p. 275).
Based on that, you have to make up the days that you fasted whilst you were bleeding, if the bleeding did not continue for the rest of the month.
If the bleeding did continue without ceasing, then you are mustahaadah, and in the next month you should do the following:
- You should stop praying and fasting for the duration of your former regular period, then do ghusl and pray. Istihaadah [non-menstrual bleeding] does not prevent a woman from praying and fasting, but she must protect herself by wrapping herself with cotton or heavy cloth to prevent the blood from spreading and contaminating her clothing or the place where she is praying.
- If she did not previously have a regular cycle, then she should learn how to distinguish between different types of bleeding, because menstrual blood is dark and thick, has an unpleasant odour, and is usually accompanied by pain (cramps), whereas the bleeding of istihaadah is lighter in colour and is thin.
So menses is the days when the blood is dark and thick; as for the other type of bleeding, it is istihaadah.
- If there is no difference in the type of blood, then she should stop praying for six or seven days, because that is the usual length of menses for women, then she should do ghusl and pray.
The woman who is mustahaadah should do wudu (ablution) for every obligatory prayer after the time for it has begun, and she may offer whatever naafil (supererogatory) prayers she wishes with that wudoo’.
For more information, please see the answer to question no. 68818.
And Allah knows best.