We have a new house and lately we have had a sewage or sulfur type smell right outside the laundry room and we have no idea where it is coming from.

Any ideas? The plumbing for the laundry and bathrooms runs right under the floor near the laundry room.

Just a suggestion, have a plumber check to see that all the plumbing for the drains are connected, I had that problem with a house I had build, and the plumbing under my bathroom was not connected, and sewage was running on to the ground under my house.