Is this a ground floor flat? If not ignore but, if so - you could have some significant damp below the floorboards on that wall which is making the atmosphere around there very humid and also keeping the temperature low. Rising damp is mostly a bit of a myth (it can happen though) but damp brickwork lower down can certainly lead to damp plaster higher up, even if it's just due to it keeping the temperature low enough to cause a dew point.
Anyway as other have said, best to keep it well ventilated - can you get vents put in at the bottom of the wardrobe for example?
Is this a ground floor flat? If not ignore but, if so - you could have some significant damp below the floorboards on that wall which is making the atmosphere around there very humid and also keeping the temperature low. Rising damp is mostly a bit of a myth (it can happen though) but damp brickwork lower down can certainly lead to damp plaster higher up, even if it's just due to it keeping the temperature low enough to cause a dew point.
Anyway as other have said, best to keep it well ventilated - can you get vents put in at the bottom of the wardrobe for example?