HI, about once a year, my 45 year old husband will develop sudden dizziness (to the point that he cannot stand up), his blood pressure shoots to 170/90, he is nauseated and has chills. This only lasts about 30 minutes or so. He is then very tired, and after resting for a few hours feels fine. Any idea what it is? His normal blood pressure is more like 135/90. Other than being overweight, he is in good health and exercises regularly. He had a complete cardio workup last year, and the doctor says his heart is in excellent shape.