This is very rare. I was given Clindamycin for a persistent dental infection that would not go away after a root canal and multiple rounds of antibiotics. My doctor (not endodontist who prescribed the clindamycin) wanted to monitor me because the risk of c.diff is higher when you were taking a lot of antibiotics prior. My doctor even agreed that it was needed, though.
It is a very aggressive antibiotic. Have you been given amoxicillin already? My endodontist said she always starts with amoxicillin since it is a broad spectrum antibiotic, then gives clindamycin if it doesn’t work, but that unless the infection is pretty severe, amoxicillin usually works.
My experience was that my doctor told me to take probiotics once a day during and for a month after taking the clindamycin. You have to take them two hours before or after the antibiotic so I would take my probiotic two hours after my first dose every day. I did have a few reactions, like mouth sores, and stomach upset a bit, but it did not last long after the antibiotics.