Hi. Thanks for your query. Noted the history and understood your concerns. Green stools and nausea is indicative of an intestinal infection. I would advise you the following in such a situation: Get review done by your Doctor as you are taking medicines yet not getting any relief. Get the stool test done and an appropriate antibiotic and probiotic cover. Use only boiled and cooled water, electrolyte solution and homemade fresh foods. Since you already have GERD and are taking Nexium, you need to take Domperidone as motility regulator and to treat nausea. Antacids taken particularly when on empty stomach can help a lot. Take curds/yogurt and banana along with activated charcoal.