Hi... To me and this is just my opinion...it sounds like you are possibly starting to dehydrate. It's a vicious cycle since the nausea gets worse with dehydration but with dehydration comes a nauseous stomach. You can't drink much bc your sick but can't get feeling better without drinking. Also sounds like maybe you have shifted into ketosis. For me anyways that has always been a nasty, gagging, horrible taste and smelly breath issue. Like I said , just my personal opinion and problems I've had with it. Try using a coffee pot for just the hot Water but instead of coffee use white TicTacs to flavor the water and freshen your mouth.
Good luck and I pray you get better by morning! Positive thoughts and prayers your way!!
❤️️Amy ❤️️