I can't offer anything about why this happens, but just wanted to let you know that I experience that "sick to my stomach" feeling too after drinking water. Not all the time because I can predict when and when not to drink it.I also have GERD and sometimes experience heartburn after drinking water at the wrong times. It happens when the water is too cold or if my stomach has been empty for too long.Does it bother you no matter what the temperature is or if your stomach is empty?