The IR camera will show up thermal differences - hence the images are real and of concern. Need photos of the external wall as there is a need to understand where the cold is coming from. The shape of the rectangular cold spot is of significant concern- missing or thin insulation or maybe condensation /damp or a localised leak. Where is the central heating pipes/ radiator, drainpipe from bathroom etc?
I attach images from my ceiling when I used an IR camera and I was not happy, so I ripped it off to reveal condensation and mould growth caused by a lack of insulation and pooled surface water on roof .
