drinking water on empty stomach especially in the morning hours may cause some pain like symptom which may not be pathological. But if after every glass of water you experience discomfort and that too in chest region, it may be something which may need looking into.Generally it happens in oesophageal disease when it is inflammed or narrowed due to reflux of acid or some other reasons. Solids are swallowed easily but liquids cause some discomfort.
You need to undergo upper GI tract endoscopy
by a gastro specialist who will visualize directly your food passage from food -pipe(esophagus
to stomach and even duodenum
and upper small intestine(jejunum).He might order for urease test for fluid extracted from stomach
Another test is Xray of stomach after barium swallow taken soon after ingesting the barium.
So you must consult.
In meantime try omeprazole
20 mg empty stomach in the morning for 7 days, and wait and see the result.If it subsides pain, you may seek help later on if needed