One possible explanation could be that you're a celiac.... or in other words, you're allergic to gluten, as many people are and don't even know it. Beer and whiskey are full of barley, which has a lot of gluten, though in the food area wheat is your main culprit. Try cutting out wheat, barley, and oats for a day or two and see if you feel better. Some symptoms of celiac disease include gastro-intestinal distress, upset stomach, behavioral problems, foggy-headedness, and dark circles under the eyes.