Knee Ligament laxity if you have problem in your legs then it might be due to ligament laxity where your legs would become very weak due to the old ligament injury and that should be treated immediately. Wear knee cap so that you will feel firm while walking or climbing stairs.
This is a general strain and for this you can follow these measures: one keep a pillow right under the knee while sleeping, next is you can keep ice in the painful area for about 5--10 minutes, if pain
still persists you can stretch your body by twisting the waist on both sides how we used to do in the school drill similarly you can try! One time you can do hot water
fermentation that would help to reduce the muscle strain.