First off, you've done a great job by proactively asking for -- and getting -- regular colonoscopies as based on a standard five year cycle.
While you were "clean" last time round, there is a chance the Dr. will find polyps. But the good news is that not all polyps are cancerous, and not all pain in the tailbone is cancer. I know, as I've had severe tailbone pain myself thanks to getting older and having broken it when I fell on ice playing hockey as a little kid. I too was concerned and had a colonscopy just to ease my mind (and beside, my mother, aunt, cousins have had colon cancer).
But the blood with the bowel movements are a concern that you've proactively addressed by arranging to get another colonoscopy this coming Monday. My advice is to simply relax and take one day at a time. If it isn't cancer and like me, your symptoms are just old age and old injuries creeping up and clobbering you, you can likely control your pain in the butt (excuse the pun) with either prescribed or over the counter NSAIDS. I
f it isn't ... well, you've likely caught the disease in the earlier stages, mostly because you've had a colonscopy 4 years earlier and most maligencies take many years to develop from a mere polyp to cancer.
Good luck on Monday, and in the meantime, relax and enjoy your weekend. :-)
Paula Jean