I agree. Find a trainer that comes into your home so they can see the behavior first hand. Until then, if you are having company, put him in another room.
I know my boy is all sweet and loving if people say his name and act normal, but when people shy away or stare at him out the corner if their eye, he assumes something is wrong and gets hesitant. Never aggressive, but he starts keeping an eye in them. Same goes for people that approach him very very slowly with a hand outstretched. He finds that's super sketchy. Like "why are you acting so weird, something must be wrong with you."
"So that others may live"