the little amount that comes out, is it very hard and dry? or is it soft? i'm asking b/c if it's really hard and dry, then it could be your rectum is compressed with hard and dry stools - just an occasional constipation that can be easily solved with a simple fleet enema or a suppository. but if it's soft or liquidy, and still you can't push it out, then that can be a different story.
first thing, it could be that it's just a one time thing, so try to wait and see if it solves on it's own. if it doesn't, and starts causing you significant discomfort and pain, then i suggest you do a fleet enema/use a suppository to release it.
an occasional constipation can happen every once in a while to any body, but as long as it only rarely happens, then there's nothing to worry about.
i think you'd may want to wait a while, maybe it's just a one time thing and will go away. only if it continues and becomes a premanent condition, then you should see a gastro doc who specialises in motility of the digestive system and esp in pelvic floor dysfunctions, or a colorectal surgeon. they can do some dinamic x rays and other tests that can find what exactly causes the obstructed defecation.
BTW, have you reciently delivered a baby?
so meantime, try to wait and see if it works out on it's own, and if not, then don't hesitate to do a small enema/suppository.
hope it works out on it's own and very soon!