I have soft stools everyday but i have to strain & i experience incomplete evacuation. this has been going on for 3 weeks. is this constipation? if not, what can it be and is it worrisome?

Constipation: Yes this is a form of constipation. How long has this been happening? Certain medications can delay gastric motility. Lack of exercise, stress, poor fiber and water intake can all contribute. Pelvic floor problems can contribute. It can be a form of irritable bowel syndrome as well. Please see a gastroenterologist for further evaluation and appropriate form of therapy.