Go to the nearest E.R.! I don't mean to scare you..but please don't rely on this forum to help diagnose you. Your symptoms could be a wide range of things...(mild to life threatening). Good luck, and please keep us updated.
I'm unsure what to tell you besides the fact that pain that bad and swelling are symptoms that shouldn't be ignored. It's possible it's related to past illnesses, but really you need to get looked at by a dr asap.