This particular problem/question has been bothering me
for the last few days. I would like to ask if you keep your
dog on a leash when walking him? You must be able to
control your dog when out in public with him, if not, he should
be kept inside a well fenced yard while you work on this
problem. A muzzle is a good idea until you get the dog and
his problem under control. A dog, once attacked by another
dog, will NEVER forget the attack. He cannot be cured of the
problems the attack has given him. You say he's o.k. when
with the trainer, but not with you alone. I would take him
back or at least talk to the trainer about more lessons for
yourself. The trainer cannot cure the dog, only help you find
ways to deal with it & let the dog live a more normal life.
Your dog is scared out of it's mind that he will be attacked
again, and so he wants to take down the other dogs before
the imagined attack happens. Just think that every dog that
your dog manages to confront & attack, just spreads the
aggression problem to another helpless dog. Please get the
help you & your dog need. I wish you good luck with dealing
with this. It can get better, but will take a real commitment &
listening to advice of a good trainer to do it.