Is purity from menstruation valid if I relied on the first three days during which there was bleeding, then I performed ghusl and did not repeat it after the bleeding stopped and a small spot of blood returned later?

Scholars have differed concerning the blood a woman sees after the expiration of her regular period. The preponderant opinion is that all blood a woman sees within the realm of possibility is menstruation. Accordingly, ghusl (ritual bath) is obligatory after seeing any drop of blood, as it is considered menses. As for what has passed, if the drop did not recur three times, it is not considered menses according to the Hanbalis, and it is permissible to adopt this less-preferred opinion after the event has occurred. However, if its recurrence was three times and it became a habit, then the missed prayers after seeing this drop, without having performed ghusl, must be made up, as they are a debt upon you.