Will be interesting to know what was in the hold (If anything) - Hopefully a manifest will surface if there was anything weird.
The strange blip on the data of 14,000 could be explained by something going off in the hold (Think someone said a previous spike was recorded by FDR due to a tyre exploding in a hold.
A rapid descent due to cabin depressurisation and something being not tied down properly (LiPOs for instance) and bashing about could cause a serious problem.
Again, the lack of contact with ATC is the confusing one, which would suggest a high likelihood of hypoxia....
Very strange - but then again, most incidents tend to be a strange train of events rather than a single point of failure.