It's because I have spent years ignoring my IBD and often going 30 times a day it has made the skin thin and I have spent a lot of time "holding a BM" till I can find a toilet so my resting sphincter pressure is very high so according to my CRS it was only a matter of time before I got a fissure....well if someone had told me about fissures and the agony involved I would have taken more care of my IBD in the first place but hey ho.
I use psyllium husk now to try and bulk up my BMs and it does work quite well at absorbing some of the water content.