A few months ago i ped blood in my stool. there was lots of it, red. now, i have been experiencing...?

something even weirder... when i go to the bathroom, all i have been able to p is this greyish slimy, stick stuff, or clumps of what looks like flesh and blood to me. other times i get a pinkish creamy discharge from my backside, and i can not go regularly. i have a colonoscopy in 2 weeks, but anyone have any guesses? (no pain, and its not internal hemmroids)