You can either take it out and see if your GERD improves and then reintroduce it later or continue using it to treat your GERD. That's what's tricky about food sensitivities. You never know what's triggering what. That's why people say to take all FODMAPS out and then slowly reintroduce things one at a time every 2 to 3 days. Be FODMAPS free and symptom free for a while (maybe 7 to 10 days) and then bring in the cabbage juice. Wait 3 days. If you have a reaction during that time then you can add cabbage to your list of things to try again at a later date.

Are you doing any bone broth, fermented foods and/or probiotics? If your gut is damaged you may want to introduce these things at some point. Bone broth provides the building blocks for healing the gut and the fermented foods and probiotics help introduce the healthy bacteria that helps you get better. Unfortunately the ferms and pros can make you gassy and feel worse for a while. I guess there is a die off factor if your gut bacteria are damaged. So be slow with those.