I was diagnosed the beginning of last year with C-diff after taking months of antibiotics for a UTI. It did clear up for me after one dosing. But if yours is a bad as you say I would do another stool sample. I understand that it could take much long to clear up then people think. I also have IBS-D and osteoarthritis and Primary Immunodeficiency which means my immune system doesn't fight virus or bacteria. By the way I'm 82