@baohomotorprovn250932 Hi OP
Have you ever heard of a "frustrated greeter" as a type of reactivity?
Just I have one of those... it looks dreadful and sounds exactly like aggression or fear reactivty however like yours my dog actually loves other dogs... he just gets immensely frustrated by being held back by the leash from greeting them
If he does greet them he is way too aroused and it can spook him and the other dog and be a poor interaction
He is very well behaved other than this just highly excitable and aroused and doesn't have triggers other than dogs
Well prey drive but that isn't reactivity
Google frustrated greeter and see what you think. It is often an overlap into barrier frustration when they see another dog
This is a really good free video series that focuses on manging walks so the dog is below threshold and techniques for interrupting their arousal before they reach the unthinking stage
I still think you are right to think about reducing or stopping walks while you seek out a behaviourist and learn new techniques of behaviour modification for your dog... your aim is to be able to help them learn to self regulated and it takes time
Stopping the dog practicing going over threshold when it sees another dog is a key first step. Let their stress hormones fade and recover your own health
You can train and practice a lot of impulse control techniques at home.. every thing builds up and helps the dog self regulate.
A good behaviourist or behavourist level trainer will give you so much confidence with this.