Is intercourse permissible during the discharge of a small amount of brownish fluid, sometimes accompanied by reddish streaks, given that the menstrual cycle is irregular and there are no menstrual pains, and is expiation required for intercourse that occurred in this situation?

Cloudy discharge during the menstrual period is considered menstruation, and the spouses must refrain from intercourse during it. However, if intercourse occurs due to ignorance that cloudy discharge is menstruation, or that intercourse during it is forbidden, or due to forgetfulness, or coercion; then there is no sin or expiation.