I frequently feel light headed and dizzy, my systolic blood pressure has been dropping into the 70`s at night while sleeping. I feel fatique and drained most of the time, my heart rate increases into 150`s at times, I tremble on occassion, my blood pressure has been ok during my dizzy spells and heart rate too most of the time. In the past year I have had two bad dizzy spells where I was extremely dizzy, diaphoretic, pale cool clamy skin, feeling extremely hot, and would have to have a normal in color urgent bowel movement afterwards. I feel on the vurge of one of those spells pretty frequently. What could be going on with me?