Have you tried applying Castor Oil? It is messy but I would think it would help. I always feel so much better after doing castor oil packs on my stomach because the oil has the ability to seep in deeply through your skin and is so good for your liver and other organs...but I would try putting it on your backside! It should be very antifungal to the critters and it doesn't wash off easily either! I would also try eating RAW GARLIC.