i was standing in queue at a shop today, and suddenly my legs went to jelly, and everything was slowly turning white, i could hardly hear anything, and i felt sick, i felt like i just wanted to drop to the ground, and i was all sweaty and could feel sweat running down my face, and my clothes were sticking to me, i went outside and sat down for 5 minutes and then i was back to my normal self... what happened to me?