These things might not be as difficult to fix as you think. Some horses do get shaken up when they change owners as you can never explain to a horse what is happening, you just expect them to go live with someone else and they'll be fine but smart horses are affected by this the most.
My horse was just like this for the first few weeks and gradually got better over a period of a few months. At first he just had no respect for my personal space and he just seemed to be ignoring me.
Keep your feet on the ground when your head's in the clouds.