Welcome at HCM.
I have read your question.It looks from your details that you are having pain at inner side of knee after running & playing.
Pain at inner side of kne can be there due to-
-Strain of medical collateral ligament at inner side of knee.
-Tear of medial meniscus(a cushion like structure in knee).
-Due to arthritis
You should do following to have relief in this-
-Avoid putting strain at your knee.
-Do warm fomentation over the knee.This will help in relieving pain.
-Apply an ace bandage over knee starting from ankle to mid thigh.Do not bind it too tightly.This may lead to swelling at foot.
-There are some exercises which should be done after relief from pain-
Hope this all will help you.
With best wishes.