Is the popping and creaking kind of like "Rice Krispies" sounds or a lot louder than that?
I had the Rice Krispies sounds when I had neck & shoulder muscle spasms.
I also had upper cervical {c1-c2} that were misaligned - probably for many many yrs. - horse fall as teenager & car accident where I hit my head on the steering wheel in my 20s.
The muscle spams were due to repetitive work injury and the c spine misalignments compounded the problems.
post #1 has links about upper cervical/c1-c2/atlas & axis adjustments
http://neurotalk.psychcentral.com/thread84-2.html
Chiropractic care info
here's one of the links-
http://www.upcspine.com/self.htm