Are the copious yellowish discharges that preceded the descent of a small amount of blood mixed with them considered menses, and do I have to make up the days I fasted and prayed during this period?

The yellowish discharge during the menstrual period is considered menstruation by the majority of jurists. Therefore, fasting and prayer are not valid during those days, and any fasts observed during that time must be made up. The end of menstruation is recognized by the white discharge (a white fluid) or by dryness (the cotton coming out clean). Upon seeing either of these two signs, ghusl (ritual bath) and prayer become obligatory.