Fallout 3: Fawkes is Missing.?

I got out of Raven Rock and Fawkes ran up to me (the normal thing). I asked him if he wanted to follow me and he declined because my karma was neutral. I have now beaten the main game (not the three Broken Steel Quests) and have good Karma. I tried to find Fawkes but he is not at the Underworld, Museum of History, or Raven Rock. I am a level 15. I use the PS3, and have the Game of the Year Edition. How can I find Fawkes?