Boudreax's Butt Paste diaper creme. Available everywhere, cheap, works better than any mega buck cycling specific chamois creme you care to name. Also, take your shorts off as soon as you get home, shower carefully and keep everything super dry down there always. Been down this road before, no fun. No problems since I adopted this regime and stuck to it religiously. You really need to take care of your undercarriage as a cyclist.