What Causes Severe Eye Twitching?

I have eye switching in my left eye. It has been going on for approximately two weeks. I've been to an eye doctor for a checkup and mentioned it, but they said it happens sometimes and should go away on it's own. That was about 1 1/2 weeks ago. I also have had vertigo symptoms about 1 1/2 ago last about 24 hours. Any ideas what could be causing these symptoms?
Thanks.