Why does my stomach hurt when i drink water?

Hard to know, but...: The GI tract has a very limited # of symptoms to signal its distress--nausea/vomiting, diarrhea/constipation, bloating, pain, fullness, bleeding, etc. Many of these characterize IBS, but are also seen with inflammatory, infectious, ischemic, malabsorptive, and functional disorders. Directed lab work, imaging, biopsies, stool studies are appropriate in excluding peptic & other non-IBS pathology.