Also - sniff around the electrical sockets and light fittings in the room - with the passage of time electrical fittings deteriorate and give off a fishy smell (aliphatic amines) - time and heat are the causes.
If the wall socket or the plug has a bad connection heat will be generated which will cause a problem like you report.
If it's fishy then it will be electrical - if it's bad eggs then a fridge hygiene issue as below...
Good Luck...., December 2015