Think it's hard to step away from medication as a kid, there are other medications. But outside of medication there are things like cannabis, supplements, herbs that have specific properties, but assuming he is a child, that's stuff that I can't recommend.
And diet hmm, there are 3 macronutrients, fat, protein and carbs, all 3 are energy sources, and you changethe balance to one of the three, and you could argue that avoiding carbs is good and slightly tipping the scale to protein is good. But again it's a child I assume, proteins are hard on the liver, a child can't tolerate the same things an adult can I feel, if a child is still growing you can't just cut something out and assume they will develop fine by using a diet that's not sufficient in everything, people go overboard in it too, and I bet by eliminating tons of stuff you end up with deficiencies which is likely far worse than the stuff you're eliminating.
I'm totally against the eyeball approach of eyeballing what you ate and then deciding based on that if it caused issues, I have had crohn for 12 years now, I got it as a kid, I'm now an adult, there is no way no how that you can reliably find foods that make your disease worse or better with the eyeball approach, you don't know how long that food has been in the small intestine, you don't know if the food was related, you don't know if it was the food or anything else you ate. If you start elimination diets you end up with nothing. At any one time there are millions of bacteria and thousands of nutrients in the small intestine, how can you possibly know what made you flare by eyeballing it. On top of that it's even more complicated because each food has different macro and micronutrients, and not every fat / protein and carb is alike. I am totally against that approach, it's like shooting an arrow blindfolded hoping you hit something. Sure, go look at studies and try to eat based on those, but making your own diet, that has never worked for me. I'm not smarter than researchers.
Probiotics is also not something that has shown much benefit in all studies, and it's often in combination with inulin that it offers benefit, inulin = carb, that can also feed certain bacteria which could make the disease worse. It's not a magic bullet.
I can't help, but I feel sometimes people go overboard because they read something somewhere from someone, going from medication when someone has bad crohn and saying "hey someone give me a quick solution like a diet instead" = recipe for serious disaster. It's not that simple.
