We bought this house 7 years ago. The house was textured and painted by the previous owner. Now we have cracks and sections of joint compound falling off of the walls and ceilings. It looks like taping joints are lifting, but when you peel back the chunks of paint and drywall mud all you see is raw sheetrock. This is happening on exterior and interior walls. I think they did not clean the walls before they skim coated. Any ideas to remove besides using a taping knife to peel and lift off this mess?