Den, could it be because you are stressed. I think a virus could cause it though. Viruses of one type or another always seem to be going round. I had a headache, earache and dizziness a few weeks ago, which seemed never ending, but they have now gone.
Hope you feel better soon. Are you trying to keep going with it? - might be better if you took to your bed and had a good long sleep - animals do this when they are not well - we are not as sensible!!
Take care xx