I agree with the colonoscopy as it is the most comprehensive evaluation of the lower GI tract.
It is possible that the bleeding can come from the external hemorrhoid, and if this is the case, a referral to a surgeon can be obtained to correct this.
If the bleeding continues, you can consider a bleeding scan, which can evaluate for vascular conditions like AV malformations that may not be seen on the colonoscopy.
These options can be discussed with your personal physician.
Followup with your personal physician is essential.
This answer is not intended as and does not substitute for medical advice - the information presented is for patients education only. Please see your personal physician for further evaluation of your individual case.
Kevin, M.D.
www.kevinmd.com