I am over the hump with my recent chronic fissure. This is what I learned this time:
1) Stay in the tub as long as necessary to stop the pain, and maybe even longer. Sometimes the pain won't stop no matter how long you are in the tub. Be strong, it will begin to work a number of days or weeks down the road.
2) Eat less food if you are bigger like me, eat lots of fiber, drink lots of water, and poop once a day. My fissure didn't start to heal until I conditioned myself to poop only once a day by eating less food.
3) It appears that the fissure is most sensitive at the edges of the cut. This is where it will get inflamed leading to spasms. The inside edge of the cut is inside me so it is covered and if it hurts you can't do much about it except either ice or warm baths. The outside of the cut is often exposed and has a skin tag at the end. Don't touch that skin tag thinking it is a hemarrhorid. If you touch it, it will likely get inflamed and could lead to spasm. It gets inflamed anyway, but no need to help it.
4) Meditation seemed to work for me, but it could also be hokum. It is worth a try. I would try to imagine that my inner sphincter (which is a horizontal diaphragm on top of the outer sphincter) was completely loose and relaxed. I seemed to have success doing this, but don't really know if it was me just getting over the hump this latest bout with chronic fissure.