Anal fissure and digestive disease.

Having functional bowel disease. Hard stool soft stool combination even in the same day. Having a tendency of developing anal fissure for little hard stool. Lateral sphincterotomy was done to cure previous anal fissure. But due to prevailing functional bowel disease and over active urinary bladder different medicines are applied as both the disease has no definite treatment. So I get hard stool many times  andand anal fissure again again and  so I have to leave all the treatment now this time fissure is not healed inspite of diltiazem cream. So my question anal fissure has no permanent cure ??? If anal fissure is permanently cured then I can continue the treatment of functional bowel problems and over active urinary bladder.