I've been drinking/eating soy milk for a few years now, why is it now messing my stomach up?

Soy contains several naturally occurring compounds that are toxic to humans and animals. The soy industry frequently refers to these toxins as anti-nutrients, which implies that they somehow act to prevent the body getting the complete nutrition it needs from a food. The soy toxins (such as phytic acid) can certainly act in this manner, but they also have the ability to target specific organs, cells and enzyme pathways and their effects can be devastating.