Hi Trenzalore,
Welcome to the forum. I'm glad you found us! I remember how relieved I was to find this site, and it's been a tremendous source of knowledge and psychological support.
It's interesting that at least a couple of people that have joined recently have mentioned stress as a factor. I did a little googling and found this page,
https://www.clinicalkey.com/topics/gast ... ssure.htmlwhich explains how anal fissures are associated with a lack of good blood supply to the anal area. That low blood supply is caused at least partly by a high anal resting pressure in the internal anal sphincter. The sphincter has to stay tight shut at all times except when we have a BM, and in some people it's just shut too tight. People with anal fissures generally have a high anal resting pressure, making the area prone to damage and difficult to heal.
Here is an interesting snippet from that page:
"Psychological stress produces a sustained tonic rise in anal canal pressure and may be one factor in the etiology of anal fissures".
Here is another site that says the same thing even more strongly:
http://drbenkim.com/anal-fissure-heal.htmI have to say that I don't think I was particularly stressed when I got my fissure, but it sounds as though there could be a trend.
You also say you haven't looked after yourself, and I think that's another trend we see - people say, "I wasn't eating right", "I was eating junk food", "I was only drinking caffeinated drinks and alcohol". In times of stress we tend to gravitate to comfort foods and drinks, and that has got to play a role.
In my case, I just wasn't drinking enough water. Only tea, coffee and the occasional beer.
So anyway, you are here now, and you can read all about how to start taking care of yourself. You can vent here when you need to, and get moral support. Find a way to deal with the stress, and start taking care of your body.
You'll get through it!