Definately open the exterior service panel to the refrigerator compartment & make sure nothing has died in there, or mold, mildew from a leaking refrigerator roof vent.
If you are sure it is coming from inside the fridge, first, if it is an ammonia smell, then the coolant is leaking and is an immediate hazzard and has to be fixed. If not, try putting crumpled up newspaper in the compartments. I had never heard of this before until I loaned a previous motorhome I had to one of my brothers. The MH broke down (under warranty) and was towed to the Ford truck center for repair. They left food, meat, ice cream, etc. in the fridge & freezer where it stayed for two weeks during the summer in Atlanta. Of course it reeked when I went to pick it back up. After cleaning it thoroughly, it still smelled and someone told me about the newspaper trick. I left it in there 2 weeks, changing it once, and no more problem.
FYI, my brother though it would be OK just to let it run on propane (Duh!!) while it was fixed & stored for pickup. I don't let anyone borrow my camper anymore.
