You could try and find out where it is coming from. Is it an outside wall? Do the gutters leak or are they blocked - does the downpipe leak (you'll need ot go out inthe rain to answer these). Is it lack of ventilation - sometimes happens in quiet corners & behind drawers & wardrobes where there is no flow of air to dry it out/ keep it fresh. Do you keep the windows open to let out the water we all produce every night? In all rooms to allow a through draft. Are air vents blocked / trickle vents on windows blocked?
Are there any radiator or other pipes nearby - cold or hot? If hot, make sure they are not lagged so they can give off the heat and dry the wall out.
Is there earth on the other side of the wall that is keeping the wall damp & cold? Is there any reason for this wall to be cold - what is on the other side of it? Can you solve that?
What is the house made of - stone or brick or modern timber? Is it insulated between the walls? Does it have a DPC - just looking for clues as to where the water is coming from.
Is there a chimney nearby that may leak (hard to tell if it leaks, but it is comon)
Lots of question , I know. Happy to hear the answers & try to help.
My first guess would be inadequate ventilation - often people close all the windows to keep the damp out, but are just sealing it in. Try to keep as much damp out of the air as you can. Keep the lids on your pans when you are cooking, don't dry clothes on the radiators, make sure the bathrooom is well ventilated, and the kitchen so that the moisture in the air can't migrate to the rest of the house.
Good luck and keep us posted.