1. you haven't mentioned about the cause of anal fissure?
2. any history of constipation
, STD's, Crohn's disease, IBS
3. Symptoms associated with fissure: although pain killers are mentioned,did you noticed any discharge (pus,blood), or any difficulty while micturition?
4. was colonoscopy/sigmoidoscopy
done to rule out any underlying disease of anus?
5. avoid straining during stools,take a stool softener
for easy passing of bowels/motions, take sitz bath regularly for 15 minutes.
6. usually fissure develops a pseudo membrane over it over a period of time so will not heal fully, so prior to surgery you can go for Anal dilatation.