I’m not help on most of this discussion, but if you really think parasites might be an issue, you could look into Diatomaceous Earth (DE). Make sure you get Food Grade. It’s a good source of silica (might see if that interferes with anything else you’re taking), and the powder will basically desiccate any big bugs in the gut – from what I’ve read, it leaves the good bugs alone. You have to handle the powder carefully, it’s really fine (like ash), and you don’t want to inhale it.
Hope you find something that works!!