Why is my 1 year old son all of a sudden being mean?

My 1 year old son is the happiest, funniest, and sweetest boy (usually). I have never once had a problem with him listening when I tell him no I may have to tell him twice but he listens and never once has he hit. He has thrown fits before where hes thrown himself back when he doesn't get his way because he is spoiled rotten but he usually gets over it in about 45 seconds. Overall though hes a good kid and is so funny. But for the past four days its like a new kid I have no idea what is going on. He will NOT listen at all. If I tell him no he keeps doing what he's doing or he gets mad and starts throwing things or tries to knock whatever it is off the table. If you smack his hand he will smack back now, hit, and pull hair. He's been not himself lately and its really worrying me. We just moved to a new state 3 weeks ago(my husband is Army) and he seemed to be adjusting well but now I'm not sure if that's what it is or not. I'm completely shocked and really upset by how he's acting. He's even stopped sleeping threw the night these past four days and is waking up screaming and crying all night long. I took him to the doctor yesterday and he checked to make sure he was healthy and didn't have an ear infection or something and he said he was fine and that his terrible two's were just starting early but I'm not sure I'm too confinced about that. Any advice would be great I just feel like he's so unhappy and it's breaking my heart. Also my mother and sister came to visit this past weekend and my mother and husband had a big fight (they do not get along) and my mother pushed my husband in front of our son and when she turned around she knocked my son down and he was hysterical so I asked her to leave because I can not have that around my son. Could this be why he's acting this way? Any help would be greatly appreciated!