Is light-red blood that appears 15 days after the initial menstrual period and was clotted at its beginning considered menses or istihadah (non-menstrual vaginal bleeding)?

The minimum period of purity (Tuhr) between two menstrual cycles, according to our view, is thirteen days. This is the opinion of the Hanbalis, while the majority of scholars hold it to be fifteen days. Since this period has passed before the reappearance of blood, this blood is considered a new menstrual cycle. The preponderant opinion is that any blood a woman sees during a time when it could be menstruation is indeed menstruation.