Is it permissible to fast when a spot of blood comes down for six days and it is not the menstrual period?

The minimum duration of menstruation is one day and one night according to the Hanbalis and Shafi'is, three days according to the Hanafis, and one drop according to the Malikis. So, if a woman experiences a single spot of blood each day with complete dryness in between, what she finds is not menstruation, and she must continue fasting. She is obligated to do what a pure woman is obligated to do. This spot of blood is impure and nullifies ablution (Wudu').