Head twitching is mostly gone - he used to completely spaz out and dash across the tank frantically, and I haven't seen him do that in a while. I do think there was a flukes issue, and I think the multiple rounds of prazi cured it. I think the remaining occasional head twitching may be from ich irritation.
I am in the process of removing all fish from the tank and running them through TTM with 3x formalin dips throughout the process. I am also treating most fish with NFG during the TTM process. I am hoping that some of the blocthyness is just a secondary symptom of ich irritation... and if not, I'm hoping formalin and NFG will take care of it.