[Buster Brown]

I would look into an animal behaviorist as a new trainer and make sure their approach is positive reinforcement. I had to do this with Buster who after a hospital stay he came back more repressive and a biter. I am a bit uncomfortable with your first trainers approach as I am wary of the pinch/poking the side as it is an aggressive behavior poking to get rid of an aggressive behavior and I have read that forcing dominance forcing them to lay down in an submissive position can break a dogs spirit. I would rather they behave because they want to rather than out of fear of me. Good luck with the retraining. Make sure they come to your house and work on the aggression trigger there at first.