Actually, peeing and not wiping doesn't do much at all - your baking soda bath may though
In fact, by peeing and not wiping, she may be intuitively trying to get herself back to normal!
The pH of a healthy vagina, just like skin, should be on the acidic side. Baking soda is a pH of 8.2, slightly on the basic side, compared to water, which is neutral at 7.0. If she's sitting and playing in baking soda water for extended periods, she may be drying herself out and changing the pH of the vagina. When the pH changes, the vagina is no longer acidic and is no longer inhospitable to bacteria, yeast, and other things.
To get her back on track, skip the baking soda in her bath. While she is at home, wipe her a few times with diluted apple cider vinegar. If the area is tender and she squawks, make the solution even more diluted and keep making it stronger each day. The final strength of the apple cider vinegar should be 1/2 water to 1/2 apple cider vinegar. For best results, use distilled or pre-boiled/then cooled water, so you don't have any bacteria in it.
Make sure you're not using any fabric softeners or using too much detergent in your laundry as well. Too much detergent leaves deposits on clothing, and that could be irritating her. If you haven't already, switch to dye free and perfume free detergent. If her clothing doesn't have major stains in it, children's and babies' clothing can be washed in baking soda, actually (adults can wash their clothing in baking soda too). Baking soda is milder in pH than detergent. Make sure all her underwear is cotton and that her jeans/pants and clothing aren't too snug, the vagina area needs some room to breathe so to speak; rather, it's for air to circulate.
As a treat for her, have her eat some yogurt too, hopefully a low-sugar one.
Hopefully she'll feel better soon.