Both knees or one knee?

Is it painful to walk down stairs? More painful going down then up?

I'd take ibuprofen just to get the swelling down - keep taking it, even if it doesn't hurt. At least 2 pills every 4-6 hours. Ice or heat it depending on what's your thing (everyone has a different opinion on ice or heat), but soaking in a tub would definitely help. Elevating it when you sleep.

Hopefully if you get all the swelling away and let it calm down, it'll just go back to normal.

No additional 720 mile rides for a while.