3 y/o cat meowing all day/night

We just moved into a new home about a wee or so ago, and since then my cat has been wandering around the place meowing day in and day out. He knows where his litterbox is and everything else that he needs, yet he keeps going around meowing. It's starting to get to the point where I can't sleep at night because of his meowing and if I try to lock him out of the bedroom he sits at my door and either scratches at it or bangs against it. I've moved around a lot since I first got him and he's never done this up until about two moves ago. I read somewhere that it's because he's still not settled in because its not 'home' to him, but he usually stops around a week in. How can I help him settle in more because I don't how much more sleepless nights I can handle.

Are there stray cats in the new neighborhood that he maybe smells??  Or do you know that if the previous occupant had a cat that he smells?  I know my cat goes insane if he gets a whiff of another cat outside our house, and he's 12 years old and deaf (and he's neutered, so it's not a sexual thing!), so he yowls and howls much louder than he used to.  We always know if a new cat shows up around the house from him trying to talk to it.

Is your cat fixed?