Was going to recommend the same as Damien above, contrast bathing is great for both swelling and pain, although I'd say keep the ice and heat on for 10 on 10 off, include elevation and consider applying a compression bandage (depending on the extent of injury sustained) if elevating ensure the knee is supported fully to prevent hyper-extending or lagging.

Ice is great way to treat trauma as it decreases swelling and slows down blood flow, where as heat increases blood flow which increases swelling/bruising :)

Knee injuries are pretty difficult to deal with as we weight bare constantly through them and if not treated correctly can cause long term damage. If servere pain is experienced then consider going to your local drop in centre for a Raymed (extention) splint +/- crutches to take the weight off the joint.

If walking/weight baring through the knee ensure you are not having to alter your gait too much due to the pain-> developing hip/groin pain or a limp.

Good luck
K