Usually In The Middle Of The Night, There's A Pain

Usually in the middle of the night, there's a pain in my right leg about 5 inches below the knee and off to the right of the chin bone. What are the causes and what can I do about it. I am an active, 71 year old female. Not overweight or diabetic. I do lots of exercises and play pickleball and tennis. It only pains me in the night after I've gone to sleep for about 4 hours.