Inhaling steam helps stave off dehydration. Sipping, just sipping, broth is helpful. I use bone broth in case of sickness usually due to nutrition.
If this is not possible, simply sip water. Slowly.
Been there.
Not sure, usually I just wait.
There's always IV, maybe pot.
You could also try an ice chip? Not terribly promising.
If none of this works, definitely see a doctor.