i also noticed a couple other people saying they had anxiety on this thread as well.. look to that as the source of your problems. Anxiety can easily cause muscles to tighten, especially the eyes because thats the only organ in the body directly connected to the brain and is heavily influenced...
Darkenergy,
Did you ever consider that anxiety was the cause of your pain? I went through 5 1/2 years so far of eyestrain that started immediately one day when I began a new job. I had been working on computers for many years before I began the job, and I've had eyestrain ever since then...