It sounds really likely that it could be hemorrhoids (hey, that's a tough word to spell - don't think I've ever typed it before!) -- but good for you for insisting on a colonoscopy and making sure you find out definitively.
Since it's all set up now, try to rest easy and not worry about
it between now and then. You already know that won't do you a bit of good. The prep isn't fun (I've done it twice) but the procedure is a breeze and they'll knock you out for it. Just don't make the mistake I did last time of telling them you want to watch it on the screen while it's happening.
Just think what a relief it will be if you get good results, which you're likely to do. No more worries about
that! It's definitely worth some nail biting meanwhile. Check back and let us know how it goes.