Blasto, Triple Therapy vs. Metronidazole again?

Ok, I need some help. I was asked by someone to come to this forum.

I have Blastocystis; still joint pain and Fatigue; first got sick and diagnozed in March.

Initially took Metronidazole (500mg) for 10 days
later took Alinia for 20 days

tested again last week by a famous parasite lab; and found Blasto again;

This time, a tropical medicine doctor--not the same dr. who initially prescribed it-- insists I must take Metronidazole 750mg for 20 days. He say that it will "definitely kill the parasite"; he has run his clinic for 40 years and said he sees at least six people with Blastocystis every week; he has own lab.

I also have another option. I can take the Australian Triple Therapy.

But one of my Dr. a friend now tells me if I keep taking all these Antibiotics , I could open myself up to more risks like a super bug. He specially warned me against Australian therapy.

Please can shed any insight? I should give Metronidazole a try first, again, this time for 20 days. I must trust a dr. who has done this for 40 years.

Yes, I know you will remind me that people on Badbugs.org say that Metronidazole does not work; I read all the stories.

But must I not trust a dr. who says that Metronidazole 750mg three times a day will kill Blasto "definitely"?