Its understandable how your bud feels around other dogs now but we can get him a little more social. First thing I would suggest is a group obedience class, the bigger the better. We need to get him around other dogs and to concentrate on what you want instead of what he wants.
Even if his obedience is top notch (in your eyes), you will still take some good info away from the class. We have Petsmart here, check into them and if they are local to you. Sign up for the adult beginners class and see what happens. If no Petsmart ask your Vet who does the biggest group class.
The trainer may ask you to put a muzzle on him depending on how bad he reacts so you might want to get him one now and starting wearing it around the house so he is used to it by the time the class starts.
HTH and Good Luck
If you need anything else let me know...