Definitely anxiety and possible depression..I had the same symptoms and went to a gamut of doctors also...MRI's EEG's CAT scans....you name it.
Come over and visit the Anxiety forum on this site. You will see many people with the same symptoms....you are not alone!
I wonder if the fear of death is playing a big part here. A lot of the symptoms you describe are related to severe anxiety. Because of how you've described this, I would deal with the anxiety first, then, if the symptoms persist, you know to look further into other possible cause. Doctors are reluctant to prescribe medication for anxiety, because it is so easy to become dependant. But maybe with a say a week's treatment on something like valium you can be calm and then you will know whether the other symptoms are related or not. If it is anxiety after all, and the drugs relieve the symptoms, don't continue valium, as it will ultimately cause you problems again. Instead learn relaxation techniques, and get counselling for your feelings about death and illness. It's horrible to contemplate, but one day, like us all, you will die. Every one of us has our own way of dealing with this inevitability, be it through religion, denial, or resignation. But obsessing about it is not benefiting you, as this is a problem you cannot solve. So why not just concentrate on the present, plan for the future, and if you don't make it, join the club, none of us make it. All that you can change is your feelings.