Headaches! Oh the headaches!

I am 16 weeks with twin girls and for the last month or so I have been getting headaches daily!  Sometimes they are so bad they make me nauseous which has never been a problem for me in any of my other pregnancies.  I have a feeling it may have something to do with my appetite being so poor.  I eat a few bites and am full and have lost 15+ pound without being sick at all.  I eat healthy foods religiously now but can't shake the headaches even when I force myself to eat.  Someone please say they feel my pain!  I also work in an office and stair at computers all day. My headaches seem to be worse weekdays than weekends. Food or computer?  I just want them gone!!!