You probably ought to be tested to rule out something else. Soy milk is cooked... the beans are crushed and boiled. It's actually the first step to making tofu - The beans are crushed and boiled and the resulting soy milk is then coagulated with a salt. That you can eat tofu and be OK, but not have soymilk is suspicious that it might be something else entirely - perhaps something that is added to the soymilk you've had.