Could The Blood In Bowels Be Due To Rectal Cancer?

Back in July I had a few cases of rectal bleeding after a bowel movement. Two were days apart and the other occurred a couple of weeks after the first. I did not experience any pain or anything, just a toilet full of bright red blood with large clots that I only discovered after I started wiping. I have regular constipation so I assumed it was hemorrhoids or something. It was a lot of blood each time, enough to fill the toilet. I went to see a colorectal surgeon in August and she looked up inside but didn t find anything. It s been almost two months since my last experience, but today I discovered another toilet full of blood after an easy bowel movement. I wasn t constipated or anything and it came out relatively easy with not too much hard pushing, even though I hadn t had a bowel movement in a while. But there was still enough blood in the toilet that it colored the water red, and it was VERY brightly colored, almost pink, with clots. Afterward, now I am feeling some lower pain in my back. However, there was no pain when I passed the bloody stool. Again, there was a LOT of blood in the toilet. I am starting to really worry about rectal cancer. Can anyone tell me what it might be? I am going to call that surgeon again and schedule a colonoscopy, but in the meantime I am so worried that I feel like crying. What am I going to do if they can t get me in right away? I don t have colon cancer in my family, but I am still really really worried. Can anyone help?