Talk to Gastroenterologist on Stool And Large Intestine

I am facing this problem from last several months. I cannot be able to pass out stool. I can feel that stool somewhere in the bottom but it does not pass out. I face this problem 2-3 days in a week. I have soft or semi solid stools (not hard). I think there is some kind of problem with my large intestine as it is not pushing the stool properly. I have taken medicine of IBS as prescribed a doctor but it showed no results. What should I do?