Hello kleeninit,
Try cleaning your fridge completely with a vinegar and water mixture (50/50). Vinegar will deodorize and disinfect the fridge. If you're not sure about the vinegar smell, don't worry it will dissipate shortly.
Follow up with the baking soda as Th3on3 suggested.
Here is an article for more
odor removal techniques you might be interested in.
and another article for
heavy duty refrigerator cleaning.Mrs. Clean