I didn't mean to freak you out, I am sorry, it is hard enough, I had hoped to be supportive of what I read through your post that your instinct was to stop the soya.
I have three children, the eldest is 10 and I don't think we are at the bottom of his gut issues yet, despite years of trying and listening to people who think they know it all, random strangers on the Internet, health professionals and alternative therapists. The truth is, no one knows everything and no one knows one answer that works for every person. Somehow we have to find the best path that we can based on the information we have and the symptoms that we see.
My youngest, born 4.5 years after the eldest, is despite everthing I learned along the way, highly reactive to a huge number of substances. He was a very cranky baby, very dribbly, very snotty, very cranky, had terrible nappies and bad skin. At my wits end, I went to a nutritionist (three in fact!!) and he was sensitive to wheat, dairy and sugar (not many skin pricks for sugar!!), later he reacted to peanuts and sesame on a more serious level. He was also reacting to chemicals. I never pursued the silent reflux route as I was determined not to go down the medication route with this as I did with my first son and then spent years fixing his stomach enzymes but I suspect, it could have been diagnosed based on what I am other health professionals observed.
The story of my eldest is less severe, he had reflux, was treated, was generally grumpy, snotty, and had loose but not horrific bowels, was prone to infections which I was reassured was on the unlucky side of normal (it wasn't). He never said he was hungry. A couple of months into his food restrictions, he said he was hungry, I probably cried, I hadn't realised his food was hurting him and when he was gulping his food / milk, it was in the false hope that it would stop the pain, but it didn't.
I cannot say that my story is the same as yours and many many children reintroduce food early and there are lots of successful stories in here.
What country are you in? (I am in Switzerland) and there is loads of support / information available about food. It is not easy, I am certaintly not saying that, but some small changes in diet make the biggest difference, I remember whooping for joy when we could have egg again!!