Cartilage piercing HURTS! HELP!?

I would remove the jewelry and put something like what you were pierced with in. Start cleaning it a couple times a day with anti-bacterial soap and make sure you get all of the soap out of the piercing. You don't want to dry it out. It's probably just irritated. It doesn't sound like its infected. Keep an eye out for any swelling, redness and pus or blood. Cartilage piercings are very temperamental, at least mine are, so just try and not to have any more run ins with car doors!