PROBLEMS WITH BREWERS' YEAST?

I had a series of migraines w/ aura  last week where I had been relatively miraine free for a while, except the usual around the period ones.  I couldn't figure what triggered them out of the blue.  I was looking at a web site that stated brewers yeast as a possible trigger.  The light went on.  I'm a vegetarian and tried a new recipe last week that called for a high concentration of powdered brewers' yeast for the sauce, about 1/2 cup.  I ate it Sun. night and all week for lunch at work.  I've never had it before (maybe in food in which I didn't know it was contained in smaller concentration).  I'm almost convinced that's what caused them.  Anyone else have problems with brewer's yeast?