Two days ago, I went to the gym. I did a very mild workout. When I was about to exit the gym, suddenly I started to disorient and then I lost my vision and hearing for around 15-20 seconds but i can feel that I was standing and i can feel my hands touching other objects. After that both were restored and i started to walk, again I lost my vision and hearing for 15 seconds, so I sat down and again they were restored. This thing happened three times to me. Then I had a little headache. I want to know what could be the reason for this?