I had one that lasted for six months during my senior year of high school. Some people thought I was faking, but I was absolutely miserable. I missed altogether 30 days of school during the second semester, and I didn't get to graduate on-time.
The first day, I thought I was going to die. Didn't know what was wrong with me. My head hurt so badly that I couldn't sit up at all or I would have to vomit. Went to the emergency room and they admitted me, first thinking that I had been in a car accident and was lying that I had not. Then they thought it was meningitis. Almost did a spinal tap, but I told them it went away after the morphine they gave me (though it only took the edge off). Went to several doctors after discharge, a neurologist, a rheumatologist. Lots of bloodwork and brain scans. The neurologist told me I had lupus, based on blood test results. The rheumatologist told me it was impossible for me to have lupus, because I was a "white girl" and only "black girls" usually have lupus. This continued for six months, all the while I was missing school, and had lost my job because I could do nothing at work but throw-up. If I went to school, I would take a pillow with me and lay my head on the desk. One of my teachers even let me lie on the floor because it was the only way I could keep from feeling sick.
One day I went with my dad to my aunt's house to pick something up, and she asked if I was feeling any better, I said no. She offered to set my neck, and I said I didn't think it would help, and that I was kind of afraid of doing it. I let her do it anyway, to humor her. The next morning it was gone. Just like that.
Since then I've had many migraines, but none that lasted quite so long. My mom believes that one must have been caused by a pinched nerve. Things that have triggered them for me are smells (vanilla especially), stress, certain foods, and lack of sleep. The only thing I can really do is go to the chiropractor or sleep it off. Excedrin sometimes helps, because I don't usually take aspirin, and the caffeine makes it especially effective as my migraines are exacerbated by caffeine withdrawal. Another thing that has helped is anti-inflammatories. I recommend Aleve, in combination with whatever analgesic you prefer. Since migraines are caused by swelling and constricting of blood vessels, the anti-inflammatory helps ease the pain a bit.