Damp smells can originate from several causes:
If the floor is suspended timber it may be that the sub floor vents are blocked or restricted. This will cause a build up of humidity within the sub floor cavity and lead to damp and musty odours. Check the external vents are clear.
Ensure that there are no plumbing leaks. Check behind appliance, washing machine and dish washer. Pipes do come loose.
Check behind the bath panel. The bath waste, or shower can leak for long periods before showing visually.
Ensure that you have adequate ventilation to the property. Condensation could be the culprit.
I hope that this will assist.
Peter Barber CSSW.,CRDS.