For me personally, I can eat moderate amounts of romaine, iceberg, and spinach, but anything else like field greens etc leave the same way you describe. Never understood these wonky food intolerances. Spring mix lettuce takes me right out. I have to avoid that stuff like the plague.
However I am in remission. Prior to remission all leafy greens were extremely 'iffy' so I stayed away.
At the same time I've often wondered if it's more of some sort of minor bacterial contamination thing that causes the pain (mild food poisoning or something) versus the lettuce itself. But the spring mix lettuce issue happened on multiple occasions until I clued into what might be causing the issue. Removing it and only consuming the three I mention above seems to be fine with my crazy system.
Diagnosed Crohns-Colitis 12-13 years ago - Past Meds: Antibiotics, Prednisone, Methotrexate, Imuran, Remicade - Current Meds: Imuran 150mg/daily, Natural: WOO/Thyme Oil, All organic food no additives as best as possible. I stopped taking probiotics as I felt they were not helping much.
“The only person you're destined to become, is the person you decide to be"