There is a 1 cm sized bump behind my left ear. i noticed it 4 months ago and it hasn't changed since. i'm also a hypochondriac?

Probably not problem: Obviously it is impossible to tell you what this is as there are many possibilities, but most 1 cm bumps in that area that don't change are benign; it is probably a cyst. There is no need to rush to the doctor, esp. if it remains stable, but the next time you see your doctor (probably in not too long a time if you are a hyprochondiac :) ask your doc to look at it and then your doc can monitor it.