How do you explain brain fog symptoms without getting brushed off?

How have you explained brain fog symptoms to a doctor so they actually took it seriously?

People see it as being tired or distracted but it feels way worse than that. Forgetting words rereading the same thing five times losing track of tasks or stopping in the middle of a sentence because your brain just quits.

Did tracking patterns make a difference or did connecting it to pain, fatigue, migraine, hormones, autoimmune symptoms or medications finally make it click?