I have... a variety of problems I don't want to go into. This causes me to have all sorts of glitches fairly regularly to the point where I'm used to bizarre qualia in almost full generality. However there is one that has happened once or twice, a kind of perfect storm, that I particularly remember.

Basically, it starts with my brain getting stuck on some particular proposition, and any alternative becoming literally unthinkable. That far happens fairly commonly and it passes in a few hours. It's fairly common among humans to have this I think, it's just not usually so arbitrary and temporary.

The problem happens if the random thing is contradictory in a sufficiently fundamental way with some other underpinning of my worldmodel, I end up deriving a contradiction, and identify is as an "inconsistency". At that point it becomes a "don't think of a pink elephant; the association leaps directly to "the principle of explosion"->"all statements are true"->"the statement that'd be worst if it was true, is true"->"I can't breath"... and since this is derived so directly from things I've fully internalized, it's as impossible to doubt or imagine an alternative to as 2+2=4, and acts in a way similar to a posthypnotic suggestion.

Luckily, there seems to be safeguards on an even deeper level preventing actual serious harm. Really, I frequently have physical pain thats far worse. But there are few things that are quite as creepy and scary than being the fabric of reality dissolving into nonsense like that.