Sure sounds like flukes - I've seen the same things and had the same symptoms, but mine have been much less intense than yours. My invaders have not been as large as yours, but maybe I'm not getting them out as well as you are.
I added in zapping (which had me dumping a HUGE amount for days... less now as I think the battle has turned) and did Humaworm. I'm due to do round two in a few weeks.
Question - are you a sushi lover? I am, have loved it for years and I've wondered if that's been the original source of my infestation.