It sounds very much to me like your dog has had an accident on these floors. Perhaps when you were not there he was excited about something and while running from one room to another he slipped on the floor and stretched one of his legs or joints sufficiently to make him afraid of doing the same thing again. This is particularly possible if your dog’s nails are slightly too long. Make sure his nails are cut as short as is possible to help aid his paw’s adhesion to the floor. After this, spend lots of time with him and try to make his distracted enough about a toy or a treat to have him accompany you over the floor. He will, with time, learn to get used to your floors again. My other suggestion is to buy him some soft shoes.