The headache

Today I woke up with my headacher precursor--a litle green dot in the middle of my field of vision, similar to what happens when you look at the sun. Then, it spreads to my peripheral vision. That's the time to take pills, pills, pills, before it starts hurting. Today, I was able to stave it off for awhile, but when I laid down for about an hour or so, it came back. Right before I was supposed to be at work. Usually, resting is the only thing that kills it, but I guess today I rested just long enough for the pills to wear off but not long enough for my body to reset. So, here I sit at work, with my vision screwy. Thankfully, the pain has subsided, mostly. Do you have any idea what this is? It happens about 2-3 times a year for me, and almost always the same, except they usually happen at night. I've been told migranes and I've been told sinus headaches. I don't know much about either.