What causes dizziness?

I get dizzy sometimes, like my equalibrium is off a bit. If I look up or sound too fast, my headspins. If it gets bad my eyes will even ratchet back and forth for a few seconds. It has happenned for several years now, and just out of the blue pops up. Any ideas? It doesn’t seem to be food related. Some days it lasts minutes, some all day. Thanks for your help!