Hormonal imbalances can also cause headaches- are you taking any birth control, other hormone medications, or is there a possibility that you're pregnant? Headaches
can also be caused by a side effect from prescription pills, withdrawal symptoms
from nicotine and alcohol (and other drugs), low oxygen levels, flu and other illnesses, and of course tension and stress. (Do you have any exams coming up- those always gave me gnarly headaches and nausea.