There's only one way to get rid of swelling, and even that won't work if you have an underlying condition. It's called RICE--rest, ice, compression (like an ace bandage) and elevation (above the level of your heart). Anti-inflammatories like Advil or Aleve can help as well, but you should consult a doctor as the dosing is dependent on a lot of things.
Were you seen by an orthopedic surgeon? Did you have x-rays and an MRI after the accident? Did anyone discuss the possibility of damage to your articular cartilage? I would have this seen to by a specialized knee surgeon. If you do it soon, it can still be considered treatment from the accident--if the wreck was the fault of another driver, you can get their insurance to cover your treatment, whether you were a passenger or a driver.
I know it feels like your options are limited because you don't have insurance. And it could be that your knee is just taking a long time to heal and has been aggravated by your job. But the only way to be sure is to see a doctor. Check with your auto insurance and that of the other driver (if there was one) so you understand what your options are.