1) Diverticular disease is caused by small bulges in the large intestine (diverticula) developing and becoming inflamed. If any of the diverticula become infected, this leads to symptoms of diverticulitis.
2) C. diff (also known as Clostridioides difficile or C. difficile) is a germ (bacterium) that causes diarrhea and colitis (an inflammation of the colon). C-diff is also contagious and it is important that the person use good hygiene to avoid spreading.
Broad based antibiotics like clindamycin and amoxicillin are known to cause C.diff because they not only kill bad bacteria but also good bacteria in the intestines.