I'm quite new to blender and I've got lots of help from here recently I appreciate a lot! The problem I'm facing now is that the corner part of my couch starts breaking or making a weird extruded shapes along the edge of the object after sculpting. When sculpting, everything looks okay but then whenever I save the file they become like this. I removed doubles and tried to recalculate or flip directions but still don't know what I missed. Or maybe it's something I have to start from the beginning again?
This file above is before I smooth the edges on sculpting mode. If I save the file after smoothing then it always changes to the file below with deformed edges.
This is the file with changed shape