As a person who prescribes Clindamycin , I hope you were warned about this drug. It's a great antibiotic, extremely effective. I'm sure you need it. I'm not sounding an alarm about that. It has side effects though. It kills all of the bacteria in your gut, good and bad, except one: Clostridium difficile (klos-TRID-e-um dif-uh-SEEL), often called C. diff. You need to take pro-biotics every day for up to six months. Otherwise the C diff will overgrow your entire gut, and cause something known as pseudo-membranous colitis, which sucks. you will probably have diarrhea. that's normal. If it has blood in it, stop taking and call your doctor.