This is Dr. David
your doctor thought it was more likely to be infection your symptoms of diarrhea.
I hope you got blood work to check for dehydration and elevated BUN and creatinine levels.
if you are dehydrated from your 9 days of diarrhea, you might need to be hospitalized for IV fluid hydration.
infection is much more likely than colon cancer.
if you start to take your antibiotics of cipro and metronidazole, you should take probiotics like philips colon health probiotics daily to prevent risk for c diff infections and diarrhea caused by antibiotics.
yes, antibiotics can kill good bacteria in your bowels and cause more diarrhea problems often.
probiotics taken daily can help prevent this.
if you have had a colonoscopy in the last 5-10 years, you might not need another colonoscopy.
colon polyps would not cause diarrhea for 9 days.
let me know if you have questions.