What was the ABV of the beer you brewed...most people don't realize that often their homebrew is more potent than the commercial beers they drink...
For example if you live in an area that has limits on the ABV of the commercial beer, like no higher than 4.5% and yours are 6, 7, 8, or more % Alcohol by volume and you drink several that could account for it....or occasionally we get people here that used to only drink light lager bmc's with a relatively low ABV and slam them down like water, find themselves in a totally different situation trying to pound back homebrews....
Other posibilites are gluten allergies, Yeast allergies, even rare but evidently in existance are hop allergies..