Your buddy ought to see a healthcare professional, I'm just some guy on the internet.

That said: here's a description of prodromal schizophrenia. Your description reads like category #2 to me.

"Prodrome phase can also be categorized in three different ways:

    Category 1 means the patient should have at least one of the following symptoms: False beliefs that random events in the world directly relate to them, odd beliefs, or magical thinking; visual disturbance; odd thinking and speech; paranoid ideation; and odd behavior or appearance.
    Category 2 includes patients who have experienced psychotic symptoms that come and go, which have spontaneously resolved within a week.
    Category 3 includes a combination of genetic risk (i.e., being the first-degree relative of an individual with a diagnosis of schizophrenia) with substantial changes in personal daily functioning in the previous year. "

https://www.verywellhealth.com/prodromal-schizophrenia-51942...

I believe running, especially long runs will cause changes in brain chemistry. Rapid increases in norepinephrine, GABA, and serotonin. I wonder if that sudden release triggers something. Same mechanism as a runner’s high

@goggins would agree

Acute toxicity due to distribution of accumulated toxin (of some kind) by the violent action of running.

Probably this House M.D. -tier answer.

It can't be House M.D. because the diagnostic isn't lupus.

Also, participated in the group differential, instead of waiting until the end of the thread to sullenly come in and tell the patient that, by the way, I figured it out, you're being fucked over by a toxin.

Seemingly more the Dr. Foreman type.

Interesting. It is common for marathon runners to experience cognitive impairment, delusions, and hallucinations. Does this occur late in the run? Is heat, altitude, or lack of fueling a factor?