Have lurked in the past, but decided to register as having a bad few days. TMI warning below.
I'm F, 33, live in the UK. Have naturally low "transit time", and I guess, a "tight butt" . Very bad combination. Have suffered with fissures since my mid teens. They'd heal pretty fast, then I'd go for many months without problems. Nowadays I'm taking Lactulose every day (and have been for the last 10 years), and it makes me go every day mostly (if it doesn't I take a bisocodyl that night), but for me NOT to tear BM needs to be really soft, borderline unformed. In the past I remember I used to have "normal" shape and size BMs, and they would not make me tear, so is it actually possible that a sphincter gets narrower due to having recurrent fissure? I feel like my butt doesn't tolerate any stretching at all.
Also feel like "remission time" (by which I mean no pain during BM, no discomfort afterwards) getting shorter and shorter. Used to be many months, then a couple of months if I'm lucky, now weeks seem like luxury. To be honest, I could almost live with the sharp pain during BM, it's the gnawing burning sensation that lingers for hours afterwards that screws my life. Do most people have that?
I'm this close to going to the doctor with it, I know I'd never commit to anything surgical(have massive surgery phobia) but have been researching ointments and think that maybe I should try that...like GTN?
p.s. you know when people use the phrase "pain in the ass".. I always think they really don't know half of it.

Hi there, 15 years is a really long time to suffer with this. From my layman opinion you may be having anal narrowing, and ointments are unlikely to fix it. I know you have surgery phobia, (most of us do), but that would be something to perhaps get therapy for, so you can move forward with a cure for your painful BMs. Please consult a colorectal specialist, you don't have to keep living in pain.