"Frequent bowel movement" is a misnomer in medicine because no strict criteria is deciding how many bowel movements you need to have during the day to meet this diagnosis . We typically say that when a patient that has more than three bowel movements a day for at least two weeks, he may be suffering from frequent bowel movements, as long as he is not taking some laxative or medication that leads to increased stool production as a side effect. As an added caveat, if a patient has had frequent bowel movements for a long-standing period, we may even start to think that this is normal behavior for the patient and then have the readjust the criteria once again. As convoluted as the running definition for frequent bowel movement may be, the numerous causes that could be behind your symptoms are even more complicated.
Underlying etiologies can range from anywhere between intestinal pathologies, problems with your brain, stress disorders or even idiopathic causes without a possible explanation . Because of the many possibilities, It is no surprise that most doctors would prefer to find the proverbial "needle in the haystack" instead try to get to the bottom of what could be causing your frequent bowel movements.
When a patient walks into my clinic complaining of frequent bowel movements, one of the first things that I had to do is decide whether this is a life-threatening condition, a side effect from a chronic disease or if it is something organic without a connection to the first two criteria. Once I have ruled out some apparent life-threatening conditions and am reasonably sure that some chronic disease of the bowels does not cause the symptoms, I start focusing on anxiety disorders as a potential cause that could be leading to this increased bowel activity.
Just think back to the last time you had to do a presentation for a crowd, whether at work or at school, ask a good-looking person for their number at the bar, or you were just stressed out from all the demands of daily life. One factor that most people can relate to is the sinking feeling you may have in your abdomen and the sudden urge to run to the nearest bathroom. Believe it or not, stress like this from the all-too-real situations I have eluded to can trigger a sudden urge to defecate because of an abrupt firing of the sympathetic nervous system. 
How to Treat Them
The only way to get to the bottom of this type of cause would be to have a solid understanding of the disease. The doctor will need to obtain an extensive history and perform a physical examination on you to make sure that more serious causes are ruled out before he can first suspect stress disorders. You can help facilitate this process by remembering and documenting times when you have these bowel movements and try to notice if any stress triggers happened before the event. Your symptoms may go away with an intervention as simple as relaxing more and taking some stress out of your life. Consulting with a psychologist could also help manage the anxiety you may feel in certain situations to better process uncomfortable situations. 
Even though a stress disorder is the most likely cause of your frequent bowel movements, that does not mean that we can automatically diagnose that you're dealing with stress without some further investigation. A very likely cause of your frequent bowel movements could be because of changes in your intestine lead to an increase in the amount of stool you produce. Conditions like Crohn's disease, Celiac disease, Ulcerative Colitis or Irritable Bowel Syndrome are just a few of the numerous conditions that can cause increased bowel activity . Patients may even start to notice diarrhea-like symptoms, and there could be changes in the color of the stool indicating that there are intestinal lesions to consider.
How to Treat It
If GI problems are the likeliest cause of your increased bowel activity, the first thing that you will need to do is consult with a gastrologist about your condition. There is a good chance you will need to have a colonoscopy for the doctor to visualize what the inside of your intestines look like and if there are any changes to the tissue that could be causing your symptoms. 
Something that could also make a big difference on the frequency of bowel movements you have during the day would be from the types of foods you are eating. If we take a glimpse at the traditional Western diet, it is full of dense carbohydrates and proteins with very little fiber consumed during the average meal. I like meat and potatoes as well, but when you eat this almost daily, you are going to start noticing more episodes of constipation as it is hard for your intestines to digest, absorb and expel the waste products . If patients take even a small amount of fiber in the form of vegetables or complex carbohydrates, there can be a drastic difference in the number of times a patient travels to the toilet because you have become so used to passing stools once every other day.
What You Can Do
Your diet plays a critical role in your bowel movement activity, so it is imperative that you try to eat a balanced diet with a mixture of carbohydrates, proteins and fiber. Patients who make a habit out of routinely eating vegetables tend to have fewer GI complications at a later age and will not be prone to have radical changes in constipation and diarrhea. 
These are just a few of the numerous possibilities that could be causing your increased bowel movements. I'll be exploring more of the numerous causes as we move through this series.