I thought it was a somewhat common medical term, but all of the sources are from SSRI withdrawl (which is likely still the same symptom, just a different reason). My apologies for leaving it ambiguous.

For me, it basically felt like my brain was misfiring when it'd respond to some sort of external stimuli (often basic work tasks). It was almost like my brain was getting a muscle cramp combined with a dose of adrenaline (think getting scared). It was almost like a thought would fire off in my brain, cascade around a bit, then never find anything. I could feel my brain searching for connections, but never making them.

My best guess is I was essentially in fight or flight mode so severely that all of my thoughts were firing off my lizard brain type reactions. My brain was reacting as if I were in a deadly situation, just trying to keep me surviving.