@Princess-Piano,
Welcome to a2k PrincessP.
Water seems to temporarily dilute the digestive system's overflow of acid and hormones, etc.... Sounds like the right direction.
I wonder how much this embarrassing systematic affliction has to do with the body's trying to work out the overflow of stress hormones that have flooded the body because of the exam process. It could be that after millenia of evolution have tailored a self defense mechanism of sorts that evolution having devised fight or flight reactions for all sorts of species for a reason and here the student has to stay in one place and afflict oneself with all this stress and one's body and instincts are trying to tell you and your body to run away from the source of stress as fast as possible.
I wonder if one had a way to prepare oneself in terms of lessening the stressful nature of these tests then these hormone based fight or flight reactions could be lessened. But then again isn't that goal the holy grail of all students and schools to make school a less stressful and more hospitable learning environment?
While we're at trying to solve the impossible we might as well try to solve world hunger, cure cancer, and bring peace to the middle east....