I used to use soy protein back when I was first getting into weightlifting, and discovered that I am actually allergic to most forms of soy protein. My symptoms included hives, rashes and eventually anemia, to add to it all the wonderful gastrointestinal symptoms to include ciliac disease (this is when the cilia of the small intestine become inflamed from an allergic reaction and cannot absorb nutrients). I was lucky that my doctor recognized the symptoms, and we were able to eliminate it from my diet and I saw the symptoms disappear in a matter of days.
If you are having adverse reactions, and you suspect it's something you have added to your regimen, stop using it and see if it goes away. I ca take soy protein in small doses, but the amount that was in the supplement drink was too much for my system. Now, I just take my protein in as natural a form as possible. Eggs are cheap, and so is chicken, turkey and fish, and they are all good for you. Soy, whey and wheat (gluten) protein, on the other hand, have been known to cause issues for a lot of people due to allergies.