As Mark points out, many of us experience this. Just yesterday I was doing a new set of stretches that involve laying flat on the floor. Shortly after starting these, the pressure in my head built to the point of discomfort.

I also get this on days when over-stimulation occurs to the point where it actually hurts to talk to someone. However, it's not as bad as in my early days following my concussion when I literally could not open any jar due to the pressure experienced during the exertion... nothing quite as emasculating to a man then having to ask his wife to open every jar for you! Good times.