I too get exhausted very easily - but am back to work full time.  Isn't it funny how everyone wants you to feel "normal" again so that life can go on?  I feel lucky that I didn't have as tough as time as many that I read about on this site.  
I had a scare also a couple a weeks ago - I felt a lump on the opposite of the neck.  Had an MRI and it bone, not a mass.  Talk about feeling like my life was over!!  I see the ENT monthly and have seen the RO once since finishing tx, won't see him again until about 6 months out.