Weird Damp Patches Appear and Have Gotten Bigger?

[EddieK19]

I am hoping some one can help me regarding damp patches appearing.

We have recently moved in to a house. We had it looked at by a surveyor. He did mention there was some damp detected on his meter but pretty much said that way it - nothing to be worried about.

Since we have moved in, 7 days ago the patches have been getting bigger and bigger and wetter and wetter (see attached for pictures).

They are in the middle of two separate walls which has recently (around 6 years I guess) been built in a small extension. The weird thing is, it hasn't rained and if anything the weather has been quite warm.

We haven't really cooked anything major....it is a bit confusing. It isn't mouldy (yet) but quite concerned how quickly it has expanded.
Both walls have brick behind them but it is new build. Any ideas of what to do and how to do it would be greatly appreciated!

[Samuel193]

I would think this has to be because of a leak, especially if they are getting bigger and wetter. From your description I din't really understand where the location of the walls were. what is located behind the walls? is is another room or is it an outside wall?