advice on drinking more water?

weird question I know. I used to drink literally about 2 liters of water or more a day when I was very into fitness about 4-5 years ago. these days though I have to intentionally make myself drink water. for some reason it used to be all I craved and it quenched my thirst and these days it makes me nauseous and I have no idea why other than maybe sensory?

I can't drink flavorless water full stop unless it is ice cold and my teeth are so sensitive that the cold is unbearably painful. (that is also a dental issue more than a sensory I'm fully aware sadly) I use flavored packets and all of the flavors I used to love are nauseating now, and I narrowed it down to those before because the other flavors were gross. the only one I still like is the lemonade one but whenever I drink a lot of water, it almost makes my throat feel weird? and it makes my stomach feel weird too, the closest feeling I can relate it to is just nausea or like I'm ABOUT to be getting sick with a cold. it just makes my mouth and throat and stomach feel really bad and therefor I just feel bad period. it also makes me feel almost weirdly empty and more hungry yet if I physically did eat I feel like it would come right back up. I use filtered watered so I don't think it's anything like that, it even happens when I drink bottled water. and I don't have any problems with any other beverage :( and again, this literally never used to happen, I used to drink water like crazy every day. :(