I'm not sure what to do, and really could use your feedback. Just outside the shower door in my upstairs bathroom, the white linoleum is showing a blob shaped yellowish discoloration, with a few small darker bluish spots throughout the blob. It is the approximate size of the floor mat we've had there, but with very irregular, blob-shaped borders. Because the mat is blue, I had always thought that the blue spots were from the dye from the floor mat bleeding onto the white linoleum. I have scrubbed the stains with everything under the sun to no avail. Upon further inspection, I now see that the stains could in fact be UNDER the linoleum, or in it, as it's almost like looking through foggy ice - the depth of the spots is further away than surface scratches etc.
There are NO other signs of water leak. The sheet rock just next to the shower is intact, as is the carpet just a foot over, there is no buckling or bubbling or raising of the linoleum, and the ceiling underneath appears normal.
We are hoping to put our house on the market soon and debating as to whether or not we should/could look under the linoleum with the fear of finding damage to the sub-flooring and discover a slow leak, which would not be covered by our insurance. Or option two, cover it all up with another layer of linoleum. This feels extremely unethical to me, but because we see no other signs of water leak (despite the YEARS of unchanging discoloration), I don't feel as if we're handing over an active problem to potential new owners. We also don't want to incur expenses of digging up to look for a plumbing problem that might not even be there.
I'm loosing sleep over this - is there anyone out there who can help me?
Why not send a few pictures of your floor to some local flooring companies specializing in linoleum flooring. There may be a simple reason this has happened.