Hi
You can do lots of things but it sounds like you need a bit of guidance. Ask your vet to recommend to you a really good qualified behaviourist so they can get to the bottom of why he is doing this. This sort of question can not be dealt with via a simple email.
However, you should be able to help the pulling using the technique described below:
Who’s walking who?
If your dog drags you along at high speed and your arms feel they are being pulled out of their sockets, STAND STILL. As soon as your dog stops choking and turns to look oddly at you, call the dog back to you and when he begins to come take ONE
The reason why your dog pulls is that it has learned that if it pulls it gets to go forwards and going forwards is a reward. So every time you allow it to pull you are reinforcing that behaviour. Therefore, you do not allow your dog to go forwards by pulling you only allow it to go forwards by walking calmly.
The dog -dog aggression is another matter and you will need to find out whether this is a frustrated response or a learned response or a fear related one etc. It can all become quite complicated. The worse thing you can do is to punish your dog every time it does this. Instead relax your grip and jolly on past.
Hope this helps a bit. To gain a clearer understanding of how complicated dog behaviour can become have a look at my book below.
Rosie Barclay