Suggest Treatment For Knee Pain

I am 14 years old and play basketball. I am 5'9" and 130 pounds. My knees hurt when I crouch down at my locker or when I have to get in my defensive stance in basketball. They do not hurt when I run or walk, just when I crouch. This has been a problem since about 3rd grade but has gotten worse. My mom thinks that physical therapy to stretch and strengthen muscles will help. What do you think?