Hi D.,
Warm, wet places tend to exacerbate a yeast issue. You can diagnose it yourself by looking at her tongue. A tongue is supposed to be pink. If it has a white coating on it (commonly known as Thrush in infants) then her little body is eaten up with it and it is showing symptoms everywhere. If her tongue is pink, then you need to look for another issue. The chlorine in the pool is a toxic chemical and can irritate a tender area quickly.
Yeast is extremely common these days. If it is yeast, you need to remove all the sugars from her diet including pastas, white breads and white potatoes and put her on a probiotic/prebiotic. It will take months to clear up a ongoing problem with yeast because it grows when it is fed and it is terribly hard to avoid the sugars that feed it.
Hope I helped...
M.
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