Hello,
Searching on the web, found that pressure ulcers or sores have almost the same etiology as anal fissures.
Despite special nutrition and therapies used there, the main concern is to remove pressure, take anti inflammatory drugs, muscle relaxants.
There is also dressing used, but it is nearly as impossible for anal fissures.
https://en.wikipedia.org/wiki/Pressure_ulcer
http://www.mayoclinic.com/health/bedsores/DS00570/DSECTION=treatments-and-drugs
Basically removing pressure by LIS, Botox, nitro and etc is the key.