Heard from my Neurologist, who said the following "refering you to Dr. Uszenski for a cardiac lifewatch monitor that you can wear for an extended period of time (usually about 3 weeks), to capture any abnormal heart rhythm. Abnormal heart rhythms can temporarily interfere with the normal flow of blood to the brain, and cause symptoms similar to what you are experiencing. These transient abnormal rhythms can also put a person at risk for strokes, esp strokes that people cannot find a reason to have had. In your case, I would be highly suspicious that this is a heart rhythm abnormality. There's something called "paroxysmal atrial fibrillation" and something called "supraventricular tachycardia" which can both cause SPELLS of dizziness/vertigo and near-passing out spells.