The Refrigerator Stinks

Three days ago, I opened the fridge to a stench I can't quite figure out. I said to Tall Cool One, "something in the fridge stinks, smell it". He gives me a funny look as if to say, "if it stinks, I don't want to smell it". "But I can't figure out what it is," I tell him. "Oh, you'll figure it out," he assures me.

That was three days ago. I've been pulling everything out that could cause the fridge to reek and have been feeding it to the dog or the chickens. Not that anything has been bad or past the "use by" date. I just can't seem to figure out what is causing that icky smell. Even when I open the freezer I can smell it. Can stuff from the freezer cause an odor? Does stuff that has covers on it stink through the covers? There is a fresh box of baking soda in the fridge - I thought that was supposed to take the stinkiness away. What can that smell be?

I am going to find out what it is today, I assure you. If I have to take everything from pickles to ketchup out, I am going to find it.