Hello. I m sorry you re not feeling well. I presume the imaging studies you referred to here were MRI and MRA of your brain. The fact that these studies were normal is reassuring, but there could be something going on outside your brain that s causing your problems. Your symptoms are suggestive of a paroxysmal cardiac dysrhythmia (an abnormal heartbeat that occurs intermittently), which your doctor wouldn t detect unless it occurred while he or she was examining you. Certain dysrhythmias can interfere with adequate blood flow to the brain and trigger neurological symptoms such as numbness, dizziness, confusion, fainting or even seizures. I d recommend you return to your doctor. Make sure you report your racing heart; further evaluation, including ambulatory heart monitoring and an echocardiogram, might be needed here. (Ambulatory monitoring entails wearing a small, pager-like device for a period of time to capture unusual heart activity; an echocardiogram is simply an ultrasound of your heart). I hope that helps, and good luck!