Hi Lee,
If possible I would check out your defrost collecting tray.
It will be sited at the back probably on top of the compressor.
The heat from thr motor (COMPRESSOR ) evaporates the defrost water collected in this tray.
You may have accidently split milk or meat juices in the fridge, which has made it into this tray, and is now stinking.
This is a common problem.
Remove the tray and give it a good wash.
Big Tone The Fridge Man, August 2008