It's unlikely that raw veggies themselves can cause such a problem. It's probably caused by mixing 2 different types of digestion: autolysis (via self-destruction of "victim's" cells by enzymes releasing out of lysosomes in victim's cells) and digestion with your own acid. Human beings are originally designed for 4 types of digestion, but the most natural one - is eating raw plant foods. It almost doesn't require any efforts from your stomach. That's why, for instance, i can devour tons of raw salad and digest it in 20 minutes, but a tiny amount of cooked food (even if it's vegan) can "lie on my stomach's bottom like a stone", and i'll have to swallow Pancreatine.Hmmmm....maybe that's why they've been bothering me? I don't know for sure, but I suspect low stomach acid, since when I eat too much raw foods they seem to sit high in my stomach like I ate mulch, and that feeling doesn't go away for a long time! Not salads, I can eat lots of greens and whatever else I add, but like eating veggie sticks with hummus - big problem! Like I beg for gas or burps and nothing comes out!
Speaking of salads, I need to make one for tomorrows lunch, and make a tahini dressing. I got a discounted bag of broccoli slaw, beets to cook, carrots and peppers. Wish I had celery, but only get that at a certain store
You could look up the info about food combining on a vegan/raw vegan diet (there is plenty of information on this subject). But honestly, for me it works the easiest way: if the food is completely raw,- then i can mix up everything, even veggies and fruits (in sane quantities, of course). It's more important that if you eat a mostly raw dish - the amount of a cooked (2nd) meal has to be very small. Nowadays, many vegan doctors admit that the most adequate nutrition plan is a so-called "10-80-10" diet, where 80% - are raw veggies, fruits, nuts and seeds, 10% - are cooked legumes, and another 10% - are cooked grains.
I'm not telling you that you should become a raw foodist, but at least you can minimize the damage to your digestive tract by wise food combining, and, if possible, by minimizing the controversy of raw and cooked foods. The more initial issues you have (such as gastritis, ulcer, any inflammatory processes, etc.),- the more it's appliable to you.
This is the 2nd thing i had been told long ago by my acquaintances (not to eat cooked meals at all), but a human being is weak, and until he has significant health issues, he won't listen to such "radical" theories. I didn't believe it either, and i still can't go raw. OTOH, it's not necessary! Just minimizing cooked veggies and products which decrease your acidity will be enough for the first time, until you figure out what is the best for you, and what to do next. You have to be prepared that your microbiome will change,- therefore, your acidity and metabolism may change too.
I don't think that those who told me all this stuff, lied to me or tried to mislead me: they have no purpose, and their job is genetic engineering,- (technically, they aren't doctors in the meaning which we're used to). I suspect, it's a matter of common sence - to trust scientists with an unbiased approach (who actually don't have a personal interest in what you're doing), than to trust our local doctors, who are so confused and illiterate, that they can kill you in order not to "mess up". It's always better to ask (for the truth) someone who is not interested in managing your bahavior patterns. I quit searching for the truth in affordable sources, as they are all the same, eventually. Moreover, even if you follow a wf pb diet (which is no doubt the best),- its parameters may vary depending on the factors you've been influenced by during your life. Your future meal plan strategy is a long and complex chain of factors, individual features and consequences that you already have been through.
...Sorry for the higgledy-piggledy response,- i hope you understand (approximately) what i'm trying to say.
As we say: "Dovjeryai, no provjeryai" ("trust, but check it out").