What Causes Rectal Bleeding In A Bowel Cancer Patient After A Colonoscopy?

Hi Im a 46yr old female who had stage 3 bowel cancer in end of 2013 after long period of misdiagnosis, followed by 6 mths cheomotherapy in 2014, also have uterine fibroids and cyst on left ovary with and diagnosed with adenomyosis in 2015 . Have had some minor rectal bleeding start around december 2016, since having a colonoscopy recently on April 10th bleeding began more progressive, after spending 4 days in hospital from 21st -24th April with no clear findings other than some colitis on colonoscopy results, was given some cortico-steroids on last day of hospital but unable to continue the as had reaction to them, am now unsure what to do, i have managed to get an appointment with my Dr on monday, am feeling very dispondant as to what it may be,