Gotogal, if you're eating fats, that could be part of the problem contributing to the diarrhea. Many people find that they can't process fats the way they did before the surgery. A low fat diet may be of help.
But the blood in the stool is another issue. You need to see your doc and get some tests done. Don't automatically jump to the 'colon cancer' idea. There are a lot of conditions that can result in blood. So get checked.
I'm so sorry you are suffering. I'm not a doctor and don't know much about this stuff but I would hope that while they investigated your symptoms last year, they did a colonoscopy. If not, that's something you might want to consider. I was terrified to have mine done last year. I had no problems whatsoever with the procedure. The worst part of the whole thing, for me, was the preparation.
Honestly, you current symptoms could be caused by a number of things including sludge/stones in the CBD, Post-Cholecystectomy Syndrome, Sphincter of Oddi Dysfunction, Small Bowel Bacterial Overgrowth, pancreatitis, etc.
If you're worried specifically about colon cancer because of your background or family history, please talk to your doctor and see about a colonoscopy.
Good luck and Godspeed,
Sam