do I have colon cancer? or C-Diff?

so about 2 months ago, I started taking clindamycin for a staph infection on my ear! about 4 days after taking the antibiotics, I started noticing differences in my stools, such as lines/indents running down the stool, and some mucus, and loss of appetite! then about 2 weeks later I started noticing blood in my stool, so i went to the ER and right away the Er doctor told me I had a C-Diff infection in my colon caused by the antibiotics, which all these symptoms can be caused by it, so  he prescribed me some flagyl for ten days, but it didnt really help, so they took some stool samples to test for the infection, but it came back negative, but the thing is, the test they gave me is only about 65 percent accurate and often times shows negative results when its relly positive! like I said I was COMPLETELY fine before taking the Clindamycin, but after taking it (its been about 2 months now) nothings been the same with my bowl movements and im so worried