Veganism not for everyone?

Hey lovelies

I’m really in need on some advice from anyone with experience/research with a majority plant-based diet. I’m trying to eat nutritious and healthy with a lot of variety but when I do I keep getting sick. I’ve found a particular sensitivity to garlic, onion, chickpeas, other beans, lentils and other grains ☹️ basically my whole diet and my favourite plant foods and I’m at loss of what to do. I have symptoms of nausea, bloating, diarrhoea and acid reflux but as soon as I go back to eating my normal Mediterranean diet with non-vegan foods my symptoms ease. Is veganism really not for everybody? What can I do because if I switch to being fully plant-based those are huge food groups that my body needs