I can't understand pelvic floor mechanism. Stabbing pain when poop - they say it is not a fissure.

Please help.

I can't understand what's going on in my body. I used to have a fissure, which was treated with a laser. Now 3 excellent proctologists can't see a fissure (anoscopy) or anything disturbing in my anus, and I have symptoms such as pain during the day and a stabbing pain or thorns during defecation. The entire Internet says it's a fissure, but doctors can't see anything.

Doctors say it's from excessively tense muscles in this area, the sphincter and pelvis.

Can someone explain to me what mechanism happens that I get stabbing during defecation? Or maybe they are wrong and I have a fissure?

:(