well my grandma had a pinched nerve in her neck, that caused headaches and she fainted one time. it was a simple visit to a chiropractor that helped.
another thing to try is take your vitamins once after every meal, they dont absorb into your system and they get peed out about three hours after meals.
stress can cause you to tense your neck and get headaches.
you could have a another mineral deficiency that is not covered in your dose of vitamins.
normally headaches are caused by a lack of minerals
dehydration can cause headaches so increase you water intake,
a sensitivity to food can cause them too. go to a naturalist doctor and they will diagnose food allergies.
try excising to get the blood flowing. sucks at first because you are miserable and in pain you dont want to get up and be active but its well worth it.
and finally check a ear nose thought doctor, it could be a sinus problem.