Luckily the soy milk I drink is non-gmo, organic-certified. It is soy, water and vanilla flavoring.
As far as the water, I filter mine at home with a purification system.
Again, my issue is that I have done all the things you’ve said to do, but for much much longer than 3 weeks, then another 4 weeks. I did all of those for nearly 4 months before I even touched soy, or oatmeal. It wasn’t until 5-1/2 months I touched a banana. The problem becomes then if I’ve done ALL that, AND done it for nearly 3-4 times longer than expected, wtf? is going on with my body?
I’ve thought, well maybe food poisoning, or a virus. The trouble is that I have no way of knowing…