Perhaps you take estrogen, birth control pills, or are going through menopause. In other words, note anything and everything that is affecting your life. After several migraines you may see a pattern that will help you and your doctor find an appropriate treatment. If not, at least you have tried the latest stress reduction technique of writing things down. No matter what is triggering your migraines, and honestly you may never figure it out, there are several things you can do that might lessen the number or severity of your attacks.
Regular exercise is one of the best.
As part of a healthy lifestyle, swimming, brisk walking or whatever exercise you favor, will generally relax you and keep your vascular system in good trim so your body will handle more effectively the changes in artery size that cause migraines. Relaxation techniques such as yoga, meditation, or relaxation training which teaches you how to reduce muscle tension can also be a help. Biofeedback works for many people. This technique uses equipment to help you monitor and modify your pulse, breathing, heart rate, etc. Once you learn it, you no longer need the equipment.