Hello There and Welcome,
Although I am no doctor to me it sounds like a few things could be the culprit 1. Could be your vision......I was having similiar problems to yours before and my eye doc gave me an eye test and he said my vision was causing my headaches after looking at TV and Computer or 2. If you get anxious even when you don't realize your anxious you unconciously tighten your muscles sometimes like in your neck, back, or shoulders.....I know this because I do this quite a bit sometimes I don't even realize doing it and if your tense you can definetly get tension headaches. But like Susan said speak with your doctor to be sure. I just wanted to offer a bit of advice and my own experience. Good Luck.

Jennifer