I realize this is a  late response, but from  a distance, this "neck bump"
sounds like torticollis (a muscle problem).
A  broken clavicle is  felt somewhere between the  shoulder joint and where
the neck starts.   The ones  I've felt  are  sort of like feeling gravel  or
something "discontinuous" under the skin.  I'll bet that very slight
fractures are  more difficult to detect.
As the bone heals a "callus" will form - that's when you feel a "bump" under
the skin.

Gail Hertz, MD, IBCLC
Hershey, PA

             ***********************************************
The LACTNET mailing list is powered by L-Soft's renowned
LISTSERV(R) list management software together with L-Soft's LSMTP(TM)
mailer for lightning fast mail delivery. For more information, go to:
http://www.lsoft.com/LISTSERV-powered.html