What Causes Sudden Episode Of Memory Loss And Tiredness?

I was driving home one night after dinner, when i had memory loss regarding my way home and difficulty driving. When I got home I felt very tired and extremely cold. My wife put a warmed blanket on me and covered me until I was warm. I fell asleep and awoke a few hours later during the night feeling extremely hot. Although we didnt take my temp, by body was hot to the touch-probably over 100 degree temp. Within the hour, my temp was back to normal. What could have caused this? I am a 75 yr old male