I have always had episodes of almost fainting and have actually fainted at times. This last time I was sitting down and after I stood up and began to walk, I felt dizzy and almost fainted. I held onto the couch and was able to sit down in case I did actually faint. The episode subsided after I sat down for a minute and I did not lose conciousness - however, my legs were uncontrollably shaking approx 10 to 15 seconds during this episode. Is this a common symptom of fainting (legs shaking - knees buckling)?