Migraine
Having migraines is, to put it bluntly, a bitch. Migraines, by the way, are not just "really bad headaches". They are a vascular problem caused by dilation of the blood vessels in the head, or at least that's one theory. They can be aggravated by, and linked to, any number of conditions, including: arthritis, allergy, chemical sensitivity, sinusitis, diet triggers, too much or too little sleep, and can have such fun accompaniments and nausea and aura. Aura can be visual, auditory, and senseory disturbances, that can range from tingling, to numbness, to bright flashing spots in front of the eyes.