Do you perhaps drink diet drinks? Crystal light/ Eat Yoplait light yogurt? Use 5 hour energy drinks? Chew gum such as Dentynne, Trident, etc.? Use breath mints such as Breath Savers? Use fat free or sugar free processed food items?
If you answered yes to any of these questions, you are ingesting a very harsh chemical loosely and inaccurately labeled as an artificial sweetener - Aspartame/Phenylalanine. Google the side effects from this chemical. It's in 6000+ food and drinks items now. It induces very serious and sometimes fatal side effects, 92 of them in fact. Headaches/Migraines is among the side effects listed.
Even if you say you don't ingest any of the items I listed above, you need to check labels for every food/snack/drink product you purchase, Aspartame is used far and wide now. As of May/2103 the Dairy Industry has been permitted to use it in their products and not disclose this info the consumer. Aspartame also hides behind a dozen or more names, second one is Phenylalanine, but also Amino-Sweet, Nutra-Sweet, Ace-K, Aspartic Acid. If you take the time to google the dangers of Aspartame, you'll see the names processed food companies use to trick the consumer into thinking a product is safe to ingest.