We have a strang ordor in bedroom, comes and goes. We found a weird pile of stuff in closet. Kind of like a pile of wet brown string. Did not look like mouse or rat mess. Smelled almost like a chemical type smell,not musty or sewer like. Cleande it up and it seamed to help. Found some more later ,this looked kind of like mouse dropping, smell came back. Cleaned it up and but smell keeps coming and going only in that room. We are on a concrete slap but there is a crack between two slabs in that room. Any ideas.

Have you asked any pros to have a look? Pest control? Plumber?