Should a woman refrain from prayer and intercourse if menstrual bleeding resumes one week after the cessation of postpartum bleeding, given that a doctor has stated this is due to hormonal imbalance and the blood has the characteristics of menstrual blood?

If the total number of days of bleeding and the intervening purity does not exceed fifteen days, it is considered one menstrual period according to the majority of scholars. You must perform ghusl after the bleeding stops, then pray and fast. If the bleeding returns, you are considered to be in menstruation again. If it stops before the fifteen days have passed, you perform ghusl and pray.