Milo was a stray, super timid dog when he came into my life 14 months ago. I estimate he is maybe 2 years old terrier mix and has a lot of energy. At first, he didn't even know how to walk on a leash. After much work, we were able to walk on trails without him charging at people when they passed in the opposite direction. About 8 weeks ago, I had surgery and stopped going on our daily walks for about 3 weeks. Then the heat of the summer forced us to start walking early in the morning instead of the evenings and due to time, I have to start work at 8 am, we walked downtown instead of the trail. Downtown is particularly quiet and I am able to change directions to avoid the occasional people we might encounter. As days have cooled off a bit in the evenings, we went back to trail last week and to my surprise, he began to charge at people again, not to every one but he does it when I least expect it. He was also doing so well when we visited the local pet friendly stores but now he seems very anxious. He is an extraordinary intelligent dog. I observed that it takes him 2 days to learn something new but he is also really stubborn when it comes to changing an old habit. He is also terrified of dogs and reacts aggressively and that's another issue we need to work on. How can I help him?