over two months of bleeding

I started having mucusy blood on my stools about two months ago, and its still continuing. I go more frequently as well now, and thier .Sometimes i have very hard small balls of stool though. I had a sigmoidoscopy, but it hurt so much that the doctor said that he only got to look up about 15 inches.  I know that thier usually supposed to look up about 24 inches. The doctor didn't see any inflamation (inflammation), so he ruled out ulverative colitis. He said that the bleeding could be coming from higher up in the colon. The blood is bright red and mixed in the stool or sitting on it. I was expecting to be told it was ulcerative colitis, and that was what the doctor was expecting to find as well. Now i have to wait until mid september to for a colonoscopy. I am anxious beyond belief. I know that seems paranoid, but i fully admit that i am probably a HUGE hypochondriac. I had blood tests done, i am not anemic or anything. I do also have mucus, and it is occasionally BRIGHT green (the mucus not the stool.) Would it be more likely that it is a tumor because colitis was ruled out? Or can a part higher up in my colon be inflammed, and its only in that one area. I'm sorry to be so paranoid, but i see this blood and i'm going more frequently, and its scaring me like crazy. Its all i can think about. I also have crampy pains under my left rib cage. Of course, i invision the tumor sitting right there. I know i'm pathetic, i'm sorry!!!!! I just can't think about anything else, and when he ruled out the colitis, i immediatly assumed that the only other option left was cancer. Does anyone know if 15 inches is long enough?? ANYTHING will be appreciated!  I'm 18.  I know the chances of me having colon cancer are extremely slim, but i don't know what else it could be now.

[BERNI]

katey,
     You should probably check for internal Hemmroids sometimes
they can (rupture internally inside the rectum) and cause the bright red blood.
Or you can also check for CHRONES DISEASE.

[Doug]

Berni is correct.