Sorry to jump into the conversation…
If the bacteria has been repeatedly exposed to the Flagyl without being completely eliminated, it has the chance to mutate and become resistant. Especially if it has been exposed to the drug more than once without being killed. So it’s possible that the Flagyl might have worked before if the dose were higher, or the course of treatment were longer, but now that the bacteria has been repeatedly exposed without being killed, it has very likely started to develop resistance. The only way to know for sure before giving your child the antibiotic would be if the lab can culture the C. diff and do susceptability testing. Does that make sense? I hope!