Put a few drops of lavender oil on her feet; the smell is calming, and babies usually react well to it. (parentingsquad.com)
A few drops of lavender oil could also be added to your toddler's bath. (verywellfamily.com)
That said, a few drops of lavender oil in 2 oz of a carrier oil like coconut can be very soothing to the skin, and very effective against yeast growth. (gentlediapering.com)