I wonder if you are underestimating the effects that stress can cause? It is not just a psychological condition-it is a very real physical one.
If your muscles are tense hour after hour, day after day, week after week etc just imagine what that is doing to you.
If massage is out, then why not try some muscle relaxants? You can get these over the counter, or from your Dr.
It is natural to try and link it to whatever the last significant event was, such as the eye, but this can also confuse the issue as it closes the mind off to other possibilities.
Try hot baths, meditation, relaxing music as well. Walks and so on to get your mind off it.
Stress and muscle tension is a major player in chronic pain, yet is so often overlooked for a more 'medical' cause.