Yikes, that does sound uncomfortable. I've had to pull over off the highway for family and friends who experienced sudden and pretty urgent GI problems, so I sympathize. And it's not just little kids or elderly folks who experience these unexpected reactions to food, even stuff they've eaten before without problems.
You might try some plain sugar stuff to ward off bonks. I often carry tubes of glucose tabs in case someone on a group ride, or a homeless person or hitchhiker, has diabetes or blood sugar bonks. In an emergency, sugar is pretty much sugar.
Instead of gels, check out Clif bars and Larabars. Most have no trendy sport fuel ingredient -- no maltodextrin, no sugar alcohols like maltitol, etc. Just sugar, grains and flavors. I like 'em for the texture and flavor too. They don't taste like sport fuel bars. And most aren't crunchy with stuff that messes with my dental work. I got tired of cracking teeth on some bars that were too sticky or had nuts that were as hard as rocks.
I used to use ThinkThin protein bars, but the sugar alcohols made me gassy. Doesn't bother me on my own, but it's embarrassing in group rides when I'd have to drop to the back of the group to avoid making my riding buds pass out.
Luckily I have no problems with Clif mocha gels with caffeine, so I buy 'em by the carton. I stick with that one type since it works for me. But it does contain maltodextrin, like most gels.
Another possible alternative might be baby food in squeeze packets with resealable tops. I tried 'em myself a couple of years ago and some aren't bad at all. The fruit and yogurt types were pretty good. Not as calorie dense as gels, but a possible alternative for folks who don't tolerate maltodextrin and sugar alcohols.
After riding with pretty much the same extended group of friends and acquaintances I have a pretty good idea of their occasional health and diet quirks. So I usually carry a mini-pharmacy even on my road bike with minimal gear. At the least it's a plastic tube for glucose tabs, with:
- a few glucose tabs
- a couple of loperamide for diarrhea
- lactase enzyme for a couple of friends who are lactose intolerant, in case we stop for pizza
- antihistamines, sudafed and bronchial asthma relief pills
- ibuprofen
- CBD for myself (I might share if I like the person enough). Works great for my chronic neck and shoulder pain.
- rescue electrolytes, usually DripDrop ORS in Mylar packets (gave one of those to a friend last week who was on the verge of heat exhaustion)
On my hybrid with larger saddle bag I often carry more of a first aid kit with bandaids, etc. And emergency toilet paper. Hey, might as well be civilized while fertilizing the woods.