I think you might be referring to the antibiotic Clindamycin. According to Mayo Clinic "Antibiotic therapy for recurrent infections may involve one or more courses of a medication. The drugs are usually different from the type of antibiotic used previously. The effectiveness of antibiotic therapy declines with each subsequent recurrence." Read more here: https://www.mayoclinic.org/diseases-conditions/c-difficile/diagnosis-treatment/drc-20351697

It sounds like that is what your doctor is doing, prescribing a different type of antibiotic than the one you had before.