Damp walls!

[Charlie96]

I need help!

i have what I think is damp on the internals walls of just one room (the bedroom) in a ground floor flat.
I first noticed these small darker spots on the walls a few months ago, placed some damp traps around the room to collect and moisture and open the window every day even on the winter to ventilate to the room, i also use a dehumidifier to collect any excess moisture in the room, but these darker patches are now on all four walls of the room and starting to appear on the ceiling.
Is it damp?
What causes whatever this is?
How can I treat it?
How can I stop it spreading anymore?

Any help would be greatly appreciated!!
Thank you

 

[JohnD]

a bedroom.

It looks like condensation but there might be a leak above.

Are the windows steamy?

How often do you open the window?

How do you dry wet washing?

What is above the ceiling, particularly the wettest corners? and what is on the other side of the walls?

Is it a modern block with concrete floors and ceilings?

Is the radiator leaking?

 

[Charlie96]

It’s a bedroom, window open everyday.
No wet washing dried in this room.
Wet washing is dried with condensing tumble dryer in another room.

 

[JohnD]

Maybe a leak then.

Is it a concrete floor and ceiling?

 

[catlad]

Its the start of mould. If you type in bedroom mould into google images you will see loads of images of that problem.

 

[KenGMac]

My vote is for Condensation.