You have not stated your height and weight. If you are overweight it may be the main reason for knee pain
at your age. Any how do this.
Identify the mid point between the ankle bone and tendons and give pressure with a blunt edge on either side of your foot for 2 minutes. Also give pressure in the web between 2nd and 3rd finger from your toe for 2 minutes. Finally give a good massage for both feet in hot water. Identify the dipping portion on the back of your knee folding. Press this dip with both middle fingers and hold your knee with your thumbs for support. Please swing 20 times morning and evenings. This will relieve your problem. Consult after 10 days.