PROBLEM COCKER SPANIEL

Question

JAXON   Jaxon is a year old male neutered Cocker Spaniel, at 16 weeks he was viciously attached by a Staff Bull Terrier and held in the Staffs mouth by his nose and shaken, in the air for approx 3 minutes.
Jaxon suffer broken jaw and loss of 2 teeth.  After he recovered from this he regained his confidence with other dogs and recovered well but......over the last few months since the attack he seem to have a split personality!
He can be the most loving dog ever just like prior to the attack and then he can fly at us as a family and bite/snarl and growl for no reason.  Could Jaxon have some sort of brain damage for being shaken at such a young age, we are at the end of our tether and we love him dearly, please help....

Answer
From what I understand this horrifying attack happened 8-9 months ago?  He's a year old now and this occurred at 16 weeks of age?

I need to know precisely how long this has been happening.  When it happens.   What is going on at home when he flips out?   You say "bite" - are we talking nips or serious biting?  

What do you do when this happens?  How long does it last?

I know this is a lot of questions (and you want answers:) but the more details I get the better I can help you.