First of all, I think you have completely overloaded the puppy with changes. Just reading your description of what you have done since Saturday made me feel nervous and overwhelmed Try slowing everything down, and let him adjust slowly to new things.
Secondly…I wouldn't force this puppy to do anything right now,force will most likely make your situation worse. He is already showing signs of resource guarding (bone on couch at MIL)...that is not good for four months old. Definitely contact the behaviorist...and make sure she is experienced with resource guarding and positive reinforcement techniques.
Sounds like he also is either going thru a fear period, or just has a naturally fearful temperament...either way try to avoid putting him in situations where he may get scared, particularly if he is fearful enough that he can't take treats from you in any given situation. You don't want to flood him with the stimulus that makes him afraid, you want to introduce him to new things slowly, with lots of reinforcement.