Is a reddish-pink discharge considered menstruation if seen at infrequent intervals, with doubt as to whether it is blood or dust, given that its appearance in the morning and evening might connect and amount to a day and a night?

If a woman sees something she suspects to be blood, the default is that she remains in a state of purity until she is certain she has seen blood. If she is certain it is blood, and it stops for less than a day and a night, it is not considered menstruation according to the majority of scholars. If it stops and then returns, and the total duration of both periods (the first blood and the returning blood) reaches a day and a night, then it is menstruation. If it does not reach this duration, it is not menstruation according to the majority of scholars. However, if she performs ghusl (ritual purification) as a precaution and to avoid the differing opinion of the Malikis, who consider such blood menstruation even if its duration is short, then this is good.