Yes, colon tumors can bleed quite a bit, at least mine did. Sometimes I would get off the toilet and the bowl would be full of blood.
But you say you just had a colonoscopy 7 months ago, which means that would have to be one fast growing tumor and usually colon cancer tumors don't grow that fast.
Colonoscopy 2/17, 5cm tumor descending
Diagnosed stage iv, liver mets 3/17
Colon resection 3/17
Told surgery not an option, get my affairs in order
Meet w/MSK team 5/01/17
Liver resection/implant HAI pump 7/17
HAI pump chemo(5rds) 8/17-2/18
Spot on chest CT 10/17
Lung biopsy (that was fun) 11/17
Nocardia bacterial infection w/spread to brain (this is serious) 11/17
IV antibiotics 12/17-2/18
Oral antibiotics 3/18-present
Clear of cancer since surgery