What Causes Pale Looks With Headache And Blurred Vision?

My wife keeps getting a pale look to her...her lips turn white and she visibly looks different. Pale and colorless. She says it comes and goes, gets very frequent headaches and blurred vision, numb figertips and shakiness. We have been trying to figure out what is going on with her for over a year but doctors cant find out what it is. She is having an episode right now. She looks extremely pale. White lips. What could this be?