Suggest Treatment For Radiating Knee Pain

my age is 25 female,height and weight is 5 feet 3 inches ,55 kgs respectively,married and house wife,i m suffering from left knee pain since 1 year,pain is continous in nature ,radiates from knee to whole legs and thighs.I dont do vigrous exercises,in my daily routine there is no such work which makes me tired,so i dont understand it real cause,so plz help me and advice line of treatment