Praise be to Allah.
If the situation is as you describe, the drops of blood that appear after becoming pure from menses are not regarded as menses, because it is not ongoing bleeding. So it does not come under the ruling of menstruation, and you have to fast and pray, and do wudoo’ for each prayer when the time for the prayer begins, like women who suffer istihaadah (non-menstrual vaginal bleeding) and those affected by ongoing urinary incontinence. And your fasting during those days is valid.
And Allah is the source of strength. May Allah sent blessings and peace upon our Prophet Muhammad and his family and Companions. End quote.
Shaykh ‘Abd al-‘Azeez ibn ‘Abd-Allah ibn Baaz, Shaykh ‘Abd al-‘Azeez Aal al-Shaykh, Shaykh Saalih al-Fawzaan, Shaykh Bakr Abu Zayd