What Is The Treatment For Bruised And Swollen Knee?

Hi, I twisted my knee 4 days ago walking the dog in the snow. It hurt pretty bad but was able to get up. It has had no bruising or swelling so I thought it would be better by now. However it is not, it hurts to bend it past a certain point and is making hard to get around with 2 little ones! Walking the steps is almost impossible. What should I do or what could it be?