Stinky Fridge

What makes a fridge stink? It could be rotten food, pungent foods, spillage of some sort and the unthinkable....critter. For two months now I have been trying to rid my fridge of a mysterious odor. Because of the odor leaching in to certain foods, I have been very careful what i have been keeping in my fridge and freezer. Thank goodness I have a deep freeze and have been able to keep frozen foods away from contamination. I have thrown out numerous items that I thought could be causing the problem yet the stink persisted. I tried baking soda, crinkled newspaper, vinegar, diluted bleach, and full strength bleach. I thought that maybe my fridge was getting too warm allowing foods to spoil quicker and the odor was venting into the freezer. Oddly enough after turning the gage to almost freezing in the fridge, the odor intensified. This is not a good sign. So today, I bleached the inside and the door of the fridge and freezer again. I allowed the fridge to set for awhile and all seamed to be going well. There was a faint smell of bleach, but not the mysterious odor from before. Fridge restarted and odor persists. Food was still out of the fridge so it is not any of the food causing the odor. My fear is a critter has crawled inside the fridge and died, and without taking the whole fridge apart i will not be able to remedy the problem. One last suggestion to me was to cut an onion and set it on a plate in the fridge. It supposedly will absorb the nasty odor in the fridge. Will post more on this method if it works. Until then I will be looking for a new fridge and hopefully will not have the same problem