This is a concerning symptom. I would recommend that you discuss this with your doctor
. Your primary care doctor
can begin an evaluation for this. If required, you may be referred to a gastroenterologist
-- a stomach/colon specialist.
One concern is that there may be inflammation in your gastrointestinal tract. Your symptoms could be consistent with proctitis - -which is inflammation of the rectum. This can occur because of a number of causes -- this includes infection (like a parasite or a bacteria known as "C. diff"), an autoimmune disease like ulcerative colitis, or simply trauma. This could also be from a mechanical problem like hemorrhoids. External hemmorhoids can cause pain and occasional itchy / burning sensations. Another possibility is that you have Irritable Bowel Syndrome -- which is a dysfunction of the colon's ability to contract normally and expel the feces. Anal fissures -- or tear in the rectal muscle -- can also cause similar symptoms.
There are many things your doctor can do to evaluate this. Important would be a good exam of the rectum. If necessary, a colonoscopy, or an internal exam of the colon may be necessary.
Luckily, many of the above mentioned problems are treatable. As such, I would recommend that you see your doctor as soon as possible. Good luck!