A bolt of lightning shoots from your temple, through your tooth, around your jaw, down to your knee. As it goes through the tooth, an explosion occurs, filling your entire head with raw, concentrated agony.
Just as your brain begins to process this, a leg forgets its purpose. You barely realize you've dropped to the ground when a scream you didn't know was there forces your mouth back open, allowing the air pressure fluctuation to begin the cycle again. All you can see is white.
After a week-long hour or so, it ends. You can go about your day, but it will happen again. Probably tomorrow. Maybe today. It will happen with no warning, and it could happen at any moment. You are acutely aware of this, every second of every day, until you save up enough money to get it pulled out of your head.