Nitroglycerin cream. I'm the (male, bi) un-happy owner of an ass with a fissure, and this stuff kept me from losing my mind a few years back. The reason an anal fissure cannot heal is that the muscle spasms. The nitroglycerin cream prevents the muscle from spasming, thus allowing it to heal. That said, I still have minor issues with mine and have been generally unable to make use of the area for penetrative sex. I feel (some) of your pain - best of luck!