Take everything very slow. Constantly talk to him, letting him know you are there and everything is alright. Over exaggerate everything he does right... reward, reward, and help him to understand what he did wrong.
Ignore it when it happens like nothing happened. It will goes away won't bother either of you.
Ignore it totally and you don't be expecting it to happen when hear some noise or taking him to new places. It's the fact that you expect it, it will happen