What Causes Sudden Light Headedness And Upset Stomach?

I am 63 yrs old. I was sitting on the couch watching TV when all of a sudden, I felt sick to my stomach, got very light headed almost to the point of fainting, and my wife said I was very, very pale. It lasted only about 5 minutes but I'm worried. I was diagnosed last year with right branch bundle block and had a heart catherization, which proved negative. Now I have a slight headache. Good appetite though.