knee pain

I played professional sports for 10 years, now I am in my mid-thirties and I am experiencing knee pain. I play basketball about 3 to 5 times a week, while playing I run and jump regularly but I can tell the knee is weak. I jump rope and I can only jump about five to six times on the right foot before the pain makes me stop. Are the exercises I can do to strenghten that knee, or do I need to get some physical therapy to help me?