Pain near Knee area, mostly from Back.

I am having a pain in the knee area , which occurs mostly when i walk too much. a click sound comes often when post and during excess walking, which subsides post taking sleep/rest for few hours. i have shown it to the doctor last year who told it as chondromalacia patella, while i consulted another doctor couple of days back who says its a normal wear and tear around knee/cartigen. he has advised me to do the exercise and taken two medicines: cartigen forte (twice a day) and CMD (once a day) i have below questions: 1. are these medicines necessary ? or can i just exercise and cure them? 2. Can these medicines cause some other side effects ? 3. how can i be sure that there is not problem as i hear click sound and always feel some mental blockage that i have some problem in my knee ?