What’s wrong with my wall?

[johnwo00]

I bought this house 6 months ago and I think I have what looks like a damp area on my wall, the plaster is exposed. I tried to smooth a layer of filler on and also primed it. Left it for a few weeks to see if it would bubble up again and you can see the plaster has just come loose off again.

Help please !

 

[sparkwright]

You need to address the damp problem, and work out where it's coming from.

Is that wall hollow, and if so, are there any pipes inside it?