Very odd chemical smell in fridge...??

[earsup]

It's a Samsung frost free fridge freezer...about 20 years old...reliable etc...a few months ago noticed a weird smell...cannot really identify it but sort of chemical smell....??...all been cleaned and put coffee and bicarb in it, in some small dishes....appliance works as usual....Any ideas...the smell attaches to food if not sealed in a container.

Is it an ammonia type smell? If so, it's very likely the gas that the fridge uses for refrigeration is leaking.

No....not amonia...almost like bad vegetables...??....a real mystery...if gas was leaking it would affect appliance and has been going on for months !!

Is there a drain hole to the back of the fridge bit at the bottom.
If there is then there will be a collection tray at the back of the fridge so water evaporates due to the heat of the motor.
This can get contaminated if there has been a spill in the fridge and smells awful.
It's usually a cheese type smell from spilt milk but it's worth checking out