The information provided here is not a replacement for a doctor. You shouldn't use it for the purpose of self-diagnosing or self-medicating but rather so you can have a more informed discussion with a professional TCM practitioner.
Because it is a herb specifically indicated to treat athletes foot as can be seen on Sichuan Chinaberry's page.
Its main actions are: Clears Damp Heat. Circulates Qi. Relieves chest, epigastric and abdominal pains. Expels parasites.