Mayo Clinic: "Migraines: Simple steps to head off the pain."<br> Cleveland Clinic: "Self-Care Treatments for Headaches," "Your Jaw May Be to Blame for Your Migraine Headaches," "Relaxation and Other Alternative Approaches for Managing Headaches."<br> National Headache Foundation: "Gum Chewing May Lead to Headache."<br> University of Michigan: "Why Your Tight Ponytail Causes a Painful Headache."<br> Harvard: "When headaches won't go away."