Suzanne, if your scope 5 years ago only got halfway up the colon then they cannot say the FC test is wrong. They haven't yet looked at several feet of bowel! I'm glad you have another scope planned. Make sure they get you well sedated so they can complete the scope.
Especially as Crohn's tends to occur in the right side of the colon, namely to say the last third to a half nearest to the small bowel.
@suzanne - I really think you should have the colonoscopy. I'm not surprised you're scared, but what you went through is a rare experience and not guaranteed to ever repeat itself. I've had five colonoscopies in total (or was it four? No, five.. I think <_<.) Four were a doddle and only one I remember waking up from in any real pain. Pleaded for more sedative, somebody gave it to me, then it was over. But even before the colonscopy begins you can ask for extra sedative and I would do so. Like kazbern, tell them you do not want to wake up.