Does a slight pinkish discharge before menstruation invalidate the fast, and does it indicate loss of virginity? Also, does masturbation invalidate the fast and require making up the day after Ramadan?

The minimum duration for menstruation according to the majority of scholars is one day and one night. If the blood does not continue for this period, it is not considered menstruation. As for masturbation, if it results in the emission of semen during the daytime in Ramadan, it invalidates the fast and only requires making up the missed day (qada'), but it does not necessitate expiation (kaffarah) because expiation is specific to breaking the fast through sexual intercourse.