On Saturday Last Week I Blacked Out 3 Times, The

On Saturday last week I blacked out 3 times, the first blackout occurred at 11.45 am my face and hair were wringing wet with perspiration. When I came to I was very week and felt bilious. The second blackout occurred at approximately 12.15 pm on the way to the doctors surgery. This time as I came to I was shaking. When my wife parked the car at the doctors, I vomited. The doctor took one look at me and called for an ambulance. I was transported to hospital. However, on the way in the ambulance I blacked out again at approximately 12.45 pm. My legs and arms were very week and I was not coherent and very emotional - crying a lot. I am a very healthy active male, 73 years old. During my stay in hospital, I have had numerous tests - none indicating the reasons for my blackouts. What is your opinion?