Is the fast considered valid if menstruation occurs before Maghrib, followed by taking a birth control pill, and the bleeding stops but discharge with a different odor and color continues?

The onset of menstrual bleeding during the day necessitates breaking the fast and requires making up for that day. Discolored discharges are considered menses if they occur within the usual period or are continuous with blood. What you experienced is considered menses because it occurred within the usual period, unless it stopped for less than a day and a night, in which case it is not considered menses.