My period lasts for seven days every 29 days and it usually begins the first day of every month. I recently had a birth control device implanted, and then I started seeing blood every day. The characteristics of the discharged blood changes every day, sometimes it is heavy and sometimes light. I have decided to calculate my period the same way I used to, but now it comes out to be ten days. After ten days, I consider the rest of the month (i.e. till I finished 29 days) to be istihadhah, then I start again. Is this the correct way to determine my period?
In general, it should be noted that if a woman with a fixed time and duration sees blood that does not have the characteristics of menstrual blood (i.e., red or dark red, warm) during the normal time of her menstruation then she should still consider it to be haydh. Any blood that is seen after the time of habit has passed (e.g., seven days) but does not exceed ten days, should also be considered haydh, even if it resembles the blood of istihadha. If the blood is seen for more than ten days then the woman should only consider the days of her habit (e.g., seven days) to be haydh and anything after that [and beyond the tenth day] to be istihadha. In this last situation, the woman will need to perform ghusl as soon as the normal time of her habit ends and act according to the rules of istihadha. If she does not know whether her menstruation will continue past ten days or not, then based on obligatory precaution, she should allow one additional day beyond her normal habit in which she would consider herself haydh. After that she should perform ghusl and act according to the rules of istihadha for the remaining days, in addition to making up salat and any fast (if the month of Ramadan) for that one day after her habit.