Knee pain during tennis game

Played a very good round of tennis today. During the second game, I felt a sharp pain in my knee. Perhaps our grueling first game was too much. Anyway, went to the bench and poured drops of Balsam Fir around my knee. Within minutes, we are back at the game again. My partners are used to me using Wintergreen and notice the smell is different this time. We finished the second game. My knee cap cartilage was damaged and worn out years ago. I know what is sharp pain in the knee that you feel as if someone is poking through your knee. I am glad I carry my oil pouch with me. You can exercise and still recover quickly from things like that if you spend time to learn and manage your own life.