Celery juice responsible for stomach issues?

Hello everyone! I've dealt with excruciating pain the last 2 months. Had gastritis-like symptoms and made a list with safe-foods and no-foods. The safe-foods weren't always safe.

I had everything tested. Blood, colonoscopy, gastroscopy. Results were in normal.

I drank CJ before (about 500ml a day) and always noticed a weird sensation in my upper stomach, also had diarrhea for 1-2 hours after drinking it. When the symptoms and pain arised, I stopped CJ. After the colonoscopy I started probiotics via protocol because everything is flushed out. It took 1.5 weeks for them to work and now I can almost eat normally again.

So I thought maybe I can also start CJ again. My facial skin loved it back then. But I'm starting slow. Yesterday I had 3 stalks and my stomach cramped a little bit and I felt slighty neauseous (I was free of pain the past 1.5 weeks). Today I went with 2 stalks and no cramps, but I'm noticing a weirdly warm sensation. I'm gonna go with 1 stalk tomorrow to see how it goes.

I'm wondering if CJ could be related to those issues. My brother made a food allergy test once and apparently is highly allergic to celery and he also dealt with diarrhea when drinking it.