I am having a CT scan on in Thursday with contrast and bit worried about the contrast as I have ME and the payback after it is not good. Alain hospital want to give a colonoscopy I have a lot of horrible things with this and I am only 4ft 10. I can't drink a gallon of this prep it will kill me, I have about a litre of water a day which is spread out. Need advice as very nervous on how I will cope with taking the prep and what I will feel like after as heard so many horror stories. Thank you