It's okay to be scared! You don't know what's going to happen! But can tell you about my experience since I had both. I had horrible IBS and cramps, pain, the worst-like you. So when I did the colonoscopy prep I was like "THIS is what people are saying is so horrible???" What you've been through is so much worse! You literally (figuratively?) just drink nasty stuff then poop until it's water. At least I did. And I had to do an enema, still not even CLOSE to the horrible IBS symptoms. A mild IBS attack is worse than all of it. And I told them I was chatty when I go under, so they gave me extra anesthesia, haha. But I do find if you tell the staff you are very anxious they will give you extra sedation. And the endoscopy I just remember swallowing the scope (it's small) and waking up. That was my experience. You should be very proud of yourself for doing this for your health. Many people refuse because they are scared, and then die from colon cancer that if caught earlier...you know the ending to this story. So good for you for being brave and taking control of your health!!! You are doing such a good thing for your body. Good luck and report back! <3