Zeasorb AF is the absolute best remedy. Relief is fast.
Amazon.com: Zeasorb Super Absorbent Powder Antifungal Treatment 2.5 oz (71 g): Health & Personal Care
In the past, I have used the strongest Tinactin or Lotramin LIQUID I could find to get through the initial onslaught. Then use the Zeasorb AF daily to keep it at bay.
Just realize, this will not be an overnight cure. It will take time.
Also, the other recommendations to wear looser underwear & clothing are a must.