I've been having my menstrual cycle every 12-14 days for the last 3 months. My normal cycle is 5 days and I flow light however, this last one I was on it for 10 days!! Now I am will be starting again, because it's been every 12-14 days. What can this be? I am only 38 years old. I went to the doctor they took my blood, she is testing for Thyroid & Enima. I don't think it has to do with either one of them, but I will soon find out.