This is Dr. David
I am sorry you have been feeling so nauseous
this could be a very bad viral gastritis infection
or it could be more serious.
if you are only drinking water, you could have electrolyte imbalances easily. you need to get some salt and sugar into your system.
the best thing is to go to the hospital emergency room
the doctors there can give you stronger anti nausea medications such as phenergan or compazine (prochlorperazine)
if you don't get better, you might need to see a GI doctor and have an upper endoscopy to look down into your stomach to check for abnormalities causing this nausea.
you also need blood work to check for electrolyte imbalances.
are you there?