I took Clindamycin for a sinus infection in 2018. Shortly after taking it, I ended up with Cdiff. I've never been so sick. I was given Flaygl for the first infection. After stopping it, three weeks later Cdiff was back. I then was given Vancomycin (Vanco) for 10 days. Again, the Cdiff returned after a few weeks, I then did the Vanco pulse and tapper method for over a month. After completing that, I was okay for about a month. But then I had a 4th bout of Cdiff. My gastroenterologist said he would prescribe Fidaxamycin (Difficid). It's expensive. $7,000 for 20 pills and the co-pay was almost $1,000. But it worked. My insurance wasn't willing to pay until I had tried Vanco. I wish medical providers would prescribe Difficid after a second round of Cdiff. And many physicians are not even using Flaygl as the first line of defense any longer. They're going right to Vanco. I also know that many dental offices are no longer prescribing Clindaymcin for infections. The rate of Cdiff is peaking after using it. I hope this info is helpful to you. If the Flagyl doesn't work, I would suggest you talk to your physician about Difficid. If it hadn't worked for me, I was going to do a fecal transplant. Just happy it happened to be the one to kill all the Cdiff spores.