@jennythelib - I think it's not so much that over-the-counter medicines or even home remedies do not work as that you should really check with your doctor to make sure that you are diagnosing yourself, or your child, correctly. While you're there, you can ask what medicine would be most appropriate and if you can try a particular natural remedy first. For instance, many women think they have a yeast infection when actually they have bacterial vaginosis - or even no infection at all, just a temporary irritation or PH imbalance.
Thrush in the diaper area is pretty common with cloth diapered babies especially. They say that using coconut oil regularly as a diaper cream will help prevent it. I've successfully used Nystatin to clear up thrush rash if it occurs, but I checked with my pediatrician first.