Dealing with Crohn's for 16+ years, and I still get new/different symptoms... it definitely keeps you guessing, that's for sure! One thing I have discovered since finding this site, is that no matter what you are experiencing, the odds are, there are others that have gone through it (if not the exact same, then at least very close to it). I couldn't even begin to guess why the upper respiratory is prone to infection though.
Good health and best of luck.