Possibly fissures? I wouldn't think a trained doctor would have a hard time giving you a conclusive diagnosis of a fissure. I'm an RN, and I can usually spot a rectal fissure. Do you have pain upon passing stool, or is the bleeding painless? Generally, fissues are very painful when having a BM.
If you do have a fissure, it is very important that you don't pass ANY hard stool for 6-8 weeks. I mean none. That might mean increasing your water intake and fiber intake, taking stool softners, Milk of Magnesia, or mineral oil. Depending on your usual bowel habits, the water and fiber alone may be enough. Or if you are ususally on the constipated side, you may need the meds. The 6-8 week period will give the fissure (or crack in the mucosa) time to heal.
If after doing this for 6-8 weeks you are still having rectal bleeding, I would definately have yourself checked. General surgeons would know what to look for most definately.
~lisa~mama to 3 boys (1/02, 5/04, 12/06)