When was the last time you cleaned--really cleaned--your refrigerator?
I mean, I used a weak bleach solution to clean the walls, and scrubbed where the ink from the milk cartons rubbed against the wall. I washed all the shelves in soapy water, and hand-dried them. I took the little bucket shelves in the door and cleaned them too. It gleamed like new. Most importantly, we did the all important throwing out of stuff that we're never going to eat again and probably has overstayed its welcome.
So, my advice to you, it's probably time to clean your fridge.