It is mechanical problem involving your knee joints and medicines hardly has any role. Main thing is how to reduce further damage to knee joints. Reduce your weight by 4-5 kg. Avoid postures which cause pain specially squatting, sitting cross legged, reduce use of stairs as far as you can.
Contrast Fomentation (Hot and Cold).
Avoid sitting Cross legged
Hams Stretching- lie straight, take the leg up, pull the feet towards yourself, with a elastic tube ornormal belt. repeat 10 times, twice a day.
Sports Taping- stretch the tape from both ends and apply on the affected area