Same thing happened to me in my office in Canton, MA. Sitting at my desk had incredibly sharp pain from top of my down the front of my face. The woman in the cubicle in front of me at the same time sort of moaned, she had a sharp pain down the back of her head. The only thing that was different that day was that we had cable installed in the break room (not too near where we sat). We are somewhat close to a very small airport. Never happened again and can't even imagine what caused this.