What is the ruling concerning my fasting and entering the third day of my menstrual period with light blood spotting before Maghrib? And am I required to perform ghusl or just wudu'?

The returning blood is considered menstruation, and she must perform ghusl after it ceases. Her fast is not valid on that day if she saw blood before Maghrib. Mere cramps are not considered; the determining factor is the sight of blood.