Sudden change in behavior

Question
We have a Boston Terrier who we rescued 6 months ago. He just turned 3 on Dec 7 (two weeks ago)and is neutered. He adjusted to our home incredibly well with not one instance of relieving himself indoors until 3 weeks ago. I think his behavior is tied to a room that I just recently made into a project room. I'm pretty sure he considered the room "his" as we often played tug of war in there and it's one of the only rooms with an area rug where he could sleep and roll around--the rest of the house has wood floors. The area rug has been moved to another room-and we'd like him to adopt this other room as his (and of course, we'd like him to stop peeing and pooping in my room). For now, we're closing the door to the project room but I'd like him to be able to hang out there too, someday. Any suggestions on how to help him adjust?

Answer
How dare you change anything in his house?  He needs reeducated.  The key to most behavior problems is approaching things using the dog's natural instincts.  Dogs see all the people and dogs in the household as a pack with each having their own rank in the pack and a top dog.  Life is much easier if the 2 legged pack members outrank the 4 legged ones.  You can learn to play the role of top dog by reading some books or going to a good obedience class. A good obedience class or book is about you being top dog, not about rewarding standard commands with a treat. Start at http://www.dogsbestfriend.com/  For more on being top dog, see http://www.dogbreedinfo.com./topdogrules.htm