I cannot have bowel movement sometimes for 3 or 4 days.

Constipation is characterized by a difficulty in eliminating stools or the absence of elimination. We should pass stools on a regular basis, which means at lease once a day. 

Those stools should be a good consistency, not too hard, not too soft. You should be able to eliminate them without any strain. The symptoms that often accompany constipation are: bloated feeling, gas, loss of appetite, slight nausea, indigestion and hemorrhoids.

Chronic constipation is not good for your general health since there is an accumulation of toxins in the body. They are a cause for headaches, bad breath and skin problems. 

Constipation also increases the risks for colon cancer. If on top of constipation, there is presence of blood in the stool (black stools), a sudden weight lost and regular abdominal pain, consult a doctor for a proper diagnostic. Constipation occurs if the stools are not eliminated inside 24 hours. 

 Here is more information on constipation