My mom and dad's house is around 35 years old. When looking at the ceiling, the studs and nail holes are becoming visible through the drywall. The drywall is discolored where the studs are. Each stud in the ceiling is visible. We have had several repair professionals out and they don't have any explanation. Also, in some places in the corner of the ceiling and walls, there is discoloration, like the drywall had water settled on it. But, fortunately, all is dry.
I have a couple of thoughts, but I'm FAR from knowledgeable. So, I'm turning to you good people. Does anyone have any ideas as to what could be causing this?