Until today I thought I was going crazy, or blind, or had mad cow disease. 4-5 weeks ago I started having both physical and mental focus issues. Every time I sat at my desk I would loose focus in terms of concentration after 15-20 minutes of work. I thought it was psychological, because I was more productive with the laptop in a coffee shop than at my desk. And my eyes could not focus. I thought my monitor was going. Today I realized that when my old desktop lamp had broken 5 weeks ago, I had ploinked an old lamp from somewhere else in the house on my desk. This new lamp had a cheap florescent bulb in it.
I changed the bulb to an energy eating incandescent and blamb, headaches gone.