Am no doctor so really don't want to comment on what your symptoms are but I can relay my own personal experience. I find that I too get a headache working on the computer for more than a hour or so. I'm not sure if it is the glare of the screen or what but as all I know is that it happens. I find that if I take a break and walk around and get physical in some way it usually disappears and then I can go back and start over. I'm not sure what your sweet drink is but if you are drinking lots of sugar laden beverages it usually will exacerbate a headache and not resolve the problem. Are you drinking lots of water during the day? Headaches are also often caused by dehydration and I find if my fluid intake isn't up I tend to get light headed and then get a headache.
Because you have such a sedentary job all day it might be wise to make sure you fit in some physical activity every day if you aren't already doing that. Everyone here knows that I am always tooting my horn about the benefits of water therapy/swimming etc. for lupies but that is one thing that really keeps me as well as possible . I find if I am not physical in some way every day I feel terrible and headaches are only one symptom.
Hope this info helps if not disregard it. Hope you find some relief soon and take care.
your friend beautifulbeluga