Just wanted to add that if it is yeast, you are only feeding it by using cornstarch on the rash. Yeast won’t necessarily spread, but does just hang on forever. If you’ve tried all the above solutions and it isn’t going away, try putting generic Lotrimin on it a couple times a day and if it starts going away, that’s what it was. If it is yeast, you will need to either bleach your diapers, or use grapefruit seed extract to kill the yeast. I finally gave up cloth because we couldn’t keep the yeast rashes away, even with changing every 1.5-2 hours.
Also, naked time is the best cure for non-yeast rashes (doesn’t work well for yeast) , we end up doing it a lot to clear the rashes faster. You can also give them a bath with baking soda in the water if it’s non-yeast, very soothing for them.