Hi Stillhoping Welcome; you asked;
Does anyone have success stories healing their fissure after long periods of time?
I'm not sure if you call 20 years a long time.......

. That's how long it took me
before I finally beat mine. Its been about three years now since my last fissure,
where before I was getting them every 4-9 months.
Patience, diligence, reserve, knowledge are just a few ingredients you will
need to really beat these monsters. I did it with diet alone but it took me that
long because of stubborness and ignorance to not want to change.
Yes your fissure will test you sorely on the diet realm. Will you even try giving
this or that up for the sake of your bum seem like an easy decision but over
time can be hard to
"mustered". (get it)
Granted you may need surgical or otherwise less invasive intervention if that
sphincter spasming will not calm down with the different creams and what not.
Learning never to strain on the stool and keeping your stool soft will go a long
way in to cutting down those spasms.
Do you really suffer with the spasms, and are they for hours sometimes? If
you really want to do this naturally then get ready for a dog fight and please
never ever tell yourself that this is it, I will not get any better than my current state.
Shoot for total healing and do not except anything less 'cause to me that's
saying ok fissures you win.
GL to you....