I took Metronidazole first and it did not work for me. Then I did Vancomycin for 10 days and that did not work. Then I did Vanco pulse and taper for 5 or 6 weeks and that did NOT work. My GI finally put me on Dificid and that worked. It's expensive and my insurance would not pay for it until I had taken Vancomycin. And even then, the co-pay was high. But it worked. Ask your physician about Dificid. I've been C-diff free since November, 2018. And I knock on wood every time I say that. Wishing you well.