Isn’t one of the main issues with carbon-monoxide that hemoglobin preferentially binds with it over oxygen, and so it doesn’t get expelled from your bloodstream via your lungs? You can tolerate quite large doses with little more than a headache, so I doubt you could overdose from internally generated amounts, but a large enough dose dangerously reduces your blood’s oxygen carrying capacity.
I was told that one way to help a young child break out of a tantrum is to ask them an odd question, something like “What color shoes are you wearing?” It does seem to work sometimes, usually by annoying them so much that they forget what they were upset about in the first place. I can well see it working for someone who needs to get out of a mental spiral.