I don't know how long you've been using the elliptical, but I was given advice like this when I hurt my knees:
Ice it and rest it when you can. I know you're probably keen on not missing exercise right now, but you won't be doing yourself any favors if you're exacerbating an injury, especially in an important joint like your knees.
Once it starts feeling better, don't get back on the elliptical until you do some strengthening for all the muscles around your knee
If you are going to continue using the elliptical, you need to concentrate on form
. That means using your glutes and your hamstrings more than your quads.