I have been suffering my bowel off on with constipation and painful attacks. I was told previously I had a 1mm polyp benign which wasn't due to the pain. I had some scar tissue adhesions on bowel I had many years ago

I am having another colonoscopy as the attacks still come and go. Otherwise my toilet habits are normal. But I go through phases constipated, feeling need to go but can't. Excrement pain in rectum and tummy. It makes me sweat and want to pass out. I have to get in shower to release myself. I had fit test of 24 but j know I do have hammering diagnosed previously. The specialist said it is not too high and doesnt feel too worried about cancer. My blood test look fine. And I had a scan that shown some fluid and build up of faeces. He said he feels it something called parasitic of the bowel where it spasms 

My letter thus morning states about bowel prep for.my colonoscopy on few weeks. Then saying I can be discharged to gp if normal. But then says risk stratification for colorectal cancer 2A. I am wondering what this means? Do they already think I have cancer. Or is it like a grading system l. If so how many levels between low and high risk it just because I saw on Google 2a means cancer is in the outside walls of colon but I have not had colonoscopy yet. Only tummy scan