I Am Having Short, 30 Second To 2/3 Minutes Of

I am having short, 30 second to 2/3 minutes of light headedness that come on with no warning. I had them 2 years ago, over the course of a couple of months, then nothing until today. Today I have had 5 of them. Unlike the Positional Vertigo that I had 1 year ago these short bouts of lightheadedness are not related to any charges in head or body position. Thank you for your help.