Morecambe is absolutely right! You need to see a Gastroenterologist as this is their specialty if your GP can't find the cause for your bleeding. It's good that you are taking this seriously and can nip whatever it is in the bud. I hope this helps and wish you all the best!
Rectal bleeding is never normal and should always be medically investigated until a firm cause is found. To learn more, google rectal bleeding and click onto any of the sites listed - the Medicinenet site is particularly informative.
Unless your doctor can positively confirm that the cause is minor (e.g anal fissure, haemorrhoids etc) I suggest that you may wish to request a colonoscopy in order to provide reassurance.
regards
Morecambe