Hi. I have experienced similar symptoms. It is absolutely the pits and can be very scary. You sound like you are dealing with an imbalance in electrolytes as well as an excess of stimulating neurotransmitters.
I would urge you to find a doctor more familiar with Adrenal Dysfunction. I worked with several ND's before I found Dr. Neville at Clymer Healing. He works via long distance and is by far the best in this field. Healing dot org
Do yourself a big favor and get in touch with him. He is wonderful and will help you to better understand your body.
Best of luck. You are not alone.