Havaneses

So I got a male puppy a week ago from supposedly a "breeder". When I first met my puppy, he was the sweetest, cutest, friendliest dog and it was love at first sight.

Three days later.....
He growls at me when I pick him up, he growls at me when I try to pet him, he has tried to attack me, he doesn't want to play with me, he doesn't wag his tail when I come home or talk to him and he is more excited to meet/play with strangers than he is with me.

Totally opposite behavior of what he was in the beginning with me. I've signed him up for puppy obedience school, and the trainer saw him today to try to help me out before classes start, and he was totally loving with her, until she started to train him. And then he began to growl at her. I've stopped reprimanding him vocally, so when he growls I'll hold him until he stops. But is there anything else I can do to make my puppy happier/less aggressive (faster than what I'm doing now). The dog trainer agreed with me after seeing the dog that he was displaying abnormal signs of aggression. She attributed this to how he was raised with his litter. I just want my dog to stop trying to take my hand off every time I touch him and for him to be happy at home with me. Any advice/suggestions?

Maybe he doesn't feel good. Has he been to the vet since you got him? If not, you should probably take him. Rather safe then sorry, the vet will probably know whats wrong. Good Luck!