I was hit by a knee during a basketball game and have since noticed a new lump in my scrotum. It does not hurt but should I do anything about it?

Hematoma. Can be collection of blood or secondary lymphedema. If it is still painful need anti-inflammatory like naprosyn (naproxen) or Ibuprofen for a short duration - if not painful need to massage groin and the area of lump daily - tough to get rid of genital edema - wear supportive garment daytime.