i had an (mostly) external one and healed it with Colloidal Silver and vitamine e. i cleaned it with CS multiple times a day and applied food grade mixed tocopherols vitamin e sfveral times a day.
every time i had a bowel movement i cleaned the area thoroughly and then sprayed it with CS. each time i showered (once a day) i applied CS then vitamin e topically. i also applied vitamin e at other times. after about two weeks of this the fissure healed and hasn't bothered me since.
the problem with this area is that the wound is constanly being exposed to unclean conditions so it cant heal. the important thing is to keep is totally clean, and with plenty of vitamin e, continuously for as long as is needed. an occasional CS ename is not enough. its the kind of thing that needs persistent care until it is healed. put some qulaity CS in a spray bottle and use it throughout the day. take it to work if necessary, i am serious. no one needs to know.