How do you hydrate adequately when liquids cause stomach pain and nausea (even with just 1-2 sips)?

My GP symptoms have been making it hard to hydrate adequately. I also have POTS and poor hydration has caused a significant deterioration in my POTS symptoms to where I’m mostly bedbound and housebound at this point. I keep bringing up the issue at my appointments but my doctors just keep telling me to “do my best” with hydration.

My best is clearly not good enough, as evidenced by just how bad things are now. I’m feeling pretty stuck and losing hope that things will improve. I keep getting told hydration will solve (or at least improve) all my problems but get no actual advice on how to deal with this from my doctors and even my dietitian.

Also, I’ve asked my GI doc, POTS doc, and even PCP about IV hydration, and they all refused.