House Trained Dog Peeing and Pooping Inside?

My 2yr old Bedlington Terrier, Alfie, was house trained, but he has recently started going out and then coming in and doing his business in the house. He does not have a particular spot, just all around the house. It's awful. I don't know what to do with him. He doesn't even make any attempt to go to the back door to let you know he wants to go out. He was castrated in June last year.

By Nina R