I would like to share a tidbit of my story. Its similar to your sons. As a toddler, I was pretty messed up. My yeast infection was so bad that my stool was entirely blood red my intestines were so inflamed, I had terrible rashes and eczema, my sinus’s and ears were so infected that I wound up in surgery a few times, and I had terrible allergies including food allergies. I was always sick. I was also constantly upset, crying, and very irate. My mother finally took me to a holistic doc that put me on nystatin, b12 shots, and what is basically now known as an anti-inflammatory diet. A year later I was pretty much normal and had a pretty normal childhood! There were a few times I got my butt really kicked by viral infections, but other than that I was fine until my teens (mercury fillings then a wicked reaction to a tetanus shot). For me, it all started from doctors shoving large amounts of antibiotics in me because I was having MAJOR inflammatory problems that started hours after my first vaccination at 6 months.
Come to find out years later I have methylation problems similiar to alot of other people that have similiar problems and also have many traits of Asperger’s syndrome.