Are the first three days of menstruation, and the subsequent four days of intermittent, odorless bleeding considered menses or istihadah (non-menstrual bleeding), and what is the ruling on brown or pinkish discharge that appears at the end of the period?

The days of your period are seven days. For three of them, the blood flows and has the smell of menstrual blood. The last four days, it is intermittent and does not have the smell of menstrual blood, and then it is a brownish or yellowish discharge at the end. Based on this, you are menstruating throughout all seven days, so you should avoid everything a menstruating woman avoids. The slight intermittence that occurs during the usual period has the ruling of menstruation, as does the brownish or yellowish discharge connected to it.