Pictures would be nice.
You do need to get a good handle on the extent of the delamination
, if in fact that is what it is.
You could walk each square inch of the cabin
top looking for soft spots. Step with the ball of your foot and make any spots that flex.
You can also try a tap test. Get a heavy washer and a marker pen. Proceed in a logical pattern tapping with the washer listening for "hollow" spots. Mark them all up.
That should give you an idea of the area. You may be in for some simple fair and fill or if it really is delamination
, a quite extensive structural repair.