Hi,
Morecambe gives some good insight. Hemorrhoids are generally accessible with a digital exam (this means the doctor’s finger reaches inside the anus to feel for the hemorrhoids) would usually be able to detect any hemorrhoids. The history of constipation is associated with hemorrhoids as well, however it can also be associated with rectal cancer, too.
Age does play a role, for screening purposes though, a scope would be recommended for those at least 50 years old. But these are for those without any symptoms at all, if you have some significant symptoms, then no matter what your age is, the scopes may make a big difference.
Stay positive.
You should get this properly checked out because rectal bleeding is never normal. You don't state your age but if you are under 40 years old then colon cancer (which everyone naturally worries about) is likely to be absent.
If your doctor is not able to reassure you that the cause of your bleeding is definitely one of the minor complaints (such as haemorrhoids, anal fissure etc) I suggest that you ask for a colonoscopy.
But do go to the doctor.
regards
Morecambe