Does the bleeding that occurred suddenly and then stopped, after recovering from a fungal infection and taking marjoram, count as menses or istihadah (non-menstrual bleeding), and are prayer and fasting permissible during it, bearing in mind that the menstrual cycle is irregular and accompanied by pain without bleeding?

The minimum duration of menstruation according to the majority of scholars is one day and one night, and this is the fatwa we adhere to. Therefore, if the bleeding stops in less than a day and a night, it is not considered menstruation. However, if the blood returns within the menstrual period until its total duration reaches a day and a night, then it is considered menstrual blood. Performing ghusl after seeing drops of blood, as a precaution and to avoid disagreement, is considered good.