Do consider other causes too. I went through a period of having a constant headache, worse when I got up in the morning. Painkillers didn't touch it. GP checked me out for anything serious, but was baffled. Eventually I went to have my eyes tested, even though I had had an eye test not long before. It turned out that my eyesight had deteriorated and I needed new glasses. It was eye strain, even though the symptoms didn't seem to indicate that.