A link to a post I put up last week. It includes a link to an article on doctors overuse of "maybe" "probably" "might be" and other vague, indefinite words. Researchers have found that when doctors are vague (they claim it's to be gentle, but I wouldn't put it past a lot of doctors to be vague to avoid lawsuits just in case they're wrong), people tend to think that they are worse off than they really are. The article says--and I firmly concur--that patients should demand specifics. For instance, your doctor put you on an antibiotic, but apparently didn't tell you why it was supposed to help or even what he thought you had wrong with you. You said the radiologist declared that it was "probably diverticultis". The next time you see a doctor, demand information. When you are prescribed medicines, know exactly what they are treating and why the doctor thinks they will work. If he says you "probably" have IBS, ask him how certain he is that it is IBS. Demand a percentage. Is he 90% certain? What other possibilities linger in that 10% of uncertainty? This is the only way you can keep from worrying yourself to death.
Thankfully colon cancer isn't one of the more common cancers and is quite rare in young people and people without a family history. If anything is causing your soft stools--besides the possibility that you didn't completely eliminate whatever parasite or bad bacteria he thought you had (both area really, really hard to get rid of)--the fact that the antibiotic almsot certainly wiped out all of the good bacteria in your gut is probably the culprit. You might want to try some probiotics for a while to see if they finish normalizing you. And I believe that diverticulitis in particular has a tendency to cause odd stool shapes. If your dr. didn't do the tests that Lil mentions, and you're still worried, then getting them certainly won't hurt anything. But before you decide on a colonoscopy (which I detest having done since it just makes you have even more diarrhea because of the laxative prep), you may just want to ask your dr. what the chances are that someone of your age, sex, race and family history would have colon cancer to begin with. The fact that you have gotten a good deal better seems to indicate you have a problem which is fairly treatable.