It sounds like the headache you got was from VR Sickness. It was mild beacause you were not moving around in real life and you were just looking at pictures. When you interact with games that are 3D and requires you to move it confuses your body. When you take off the goggles or well you have them on you can easily get sick. They had to take some 3D games away from Disney world because they were making people sick.