I'm another one who has problems with artificial sweeteners - so I avoid them even more strictly than I avoid sugar.

(Insomnia, hyperactivity, trembling and headaches)
But that doesn't mean you will have the same experience.
There are a number of drinks that use stevia as a sweetener nowadays, including some sodastream cordials.
Have you tried the natural/not synthetic flavourings that you add to sparkling water? Have a google for 'aromhuset'. I bought mine from Amazon.
Also, bovril, beef or chicken varieties. Miso soup. Good quality stock cubes in hot water, as broth.
I find it easier in the summer. Winter, I too get sick of water.