Can drinking one soda help flush a stone out or would it make the kidney worse? would it help dilate and help stone move?

Any fluid helps: When trying to pass a kidney stone, drinking extra fluids of any kind increases urine production, resulting in an increased pressure head down the ureter tube to the stone, and dilates the ureter somewhat. All of this facilitates passage of the stone, assuming it is of passable size. Addition of the prescription drug Flomax relaxes the ureter tube and adds to the benefit of extra fluids.