Over The Last Several Years I Have Experienced Episodes Of

Over the last several years I have experienced episodes of light headedness, dizzy spells with a slight raise in body temperature. Sometimes sweating sometimes not. My blood pressure will rise also but once the "spell is over " I feel ok but usually have a headache afterwards. They don't usually last but a minute or two and are gone. Yesterday at work I had "a spell" that lasted 20 minutes and it was worse than any of the others. I was soaked from the sweat that was on me and I had a dizzy, swimmie feeling like I was falling but not passing out. My blood pressure they said was high as well as my heart rate but at the er it was back to normal range. I do take bp medicine( lisinopril 10 mg) . My co workers said I was talking and crying I don't remember much of it and was nauseated after about 5 min of the dizziness. This was made worse by them wheeling thru the plant where I work, so I had the dry heaves. I have been to a heart dr and worn a monitor and had, I believe an echo done he said everything looked fine. Have also had blood work for a heart attack and ekg done after this episode that were negative. Ct scan showed nothing either...... So I'm at a loss along with my Dr. I understand that these tests are sometimes wrong. After this last spell I had a terrible headache and slept a lot . Very tired. Also, ever once in a while I have an irregular heart beat. A pounding for 2 to 3 beats and then it's gone.