It sounds like you have what is called a Tension Headache. Tension headaches are caused by muscles that contract in the head and neck region.
Tension headaches can be brought on by staring at a computer screen for too long or even driving too long.
If you're working on your computer or even just playing your computer too long it can cause your headaches. You should always take a break from looking at your computer screen and look out a window or step outside and look around.