Is he fixed?
Time to steam clean and get all the residue out - remember they have sensitive noses. Then, I would find a way to confine him to a limited area in the house. Don't let him have the run of the house - he hasn't earned it yet.
Keep an eye on him to get to know his signs - and they may be subtle. As soon as he shows signs of "gotta go" (or on a schedule) take him outside. When he does his business - praise praise praise and for you patience patience patience.