Hello! Ive recently discovered a pea sized, hard, immobable lump on the back of my wife s neck (the place where the scull connects with the neck, more to the right side). The lump is immovable, as if it was cojoined with bone. It is hard to push, and not painful unless pushed hard. My wife is 20 years old. What may be the possible causes, and should we consult the doctor immediately? Thank you.