So, I promised myself I'd come back to this forum after I was SURE my fissures were resolved, since there are so many more upset and depressed posts than success stories (not many people come back once they're cured.) I especially want to let people know that traditional advice for constipation can actually make things much worse for some people.
I suffered from extremely itchy fissures through the end of 2013 and most of 2014, following a change to a lower-carb, high-fiber diet. I only had a few episodes of spasms - my problem was mainly painful, bloody BM's and all-day intense itching, along with chronic constipation. I tried fiber supplements (with lots of water), but they only seemed to make my BMs huge, and kind of explosive, which tore things up horribly. Kondremul, and Mega-dose Vitamin C were okay, but I only got really effective constipation relief from Miralax. However, the itching continued to be terrible, for months and months.
I tried Diltiazem ointment, but it didn't seem to make much difference. A dermatologist put me on topical steroids and immunosuppressants, which eliminated the itching, but it wasn't a good long-term solution, since I didn't like being on these drugs indefinitely.
After nearly a year of elimination diets and trial-and-error, I discovered that my fissures were being irritated and kept open/itchy by the soft stools I was passing due to my beloved Miralax. My IBS tends to fluctuate between diarrhea and constipation, so apparently the constipation would cause the fissures, and the diarrhea would irritate them and make them itchy and inflamed.
Strangely, eliminating fiber from my diet cured my constipation. Cutting out cruciferous vegetables in my veggie juices (I was trying to be really healthy) got rid of my random diarrhea. I have since weaned off all my medications and laxatives, using only topical Vitamin E oil from time to time, and have been able to figure out that most high-ish fiber food is actually fine for me, but lots of lettuce salads or harsh raw veggies plug me up almost instantly.
After more than a year of embarrassed, distracted misery, I'm so happy to be symptom free for 10 months now! The weird thing was that it was by going contrary to all the normal constipation advice.