sounds like you have a few legitimately fearful experiences that anyone would become more fearful and vigilant after. Nothing to be ashamed about. It is a normal human reaction to be on high alert after seeing the shootings. However, you cannot let this ptsd create patterns in your brain and wire in that manner long term as it will cause anxiety problems down the rode. So go find a good Cognitive Behavioral Therapist to talk to so that he can help you untangle those thoughts and help you not get stuck in fear and paranoia which can severly limit your life moving forward.
That's too bad. I think we all have fears and they can even be intense. I have a fear of snakes, for example. I think I see one and I have a base level reaction of fight or flight (flight takes over, I run screaming). It's real, I have a large reaction. But it doesn't come up often. Yours does, it sounds like. That's when anxiety and a phobia should be considered a real issue is if it impacts our life in a substantial way. Now, I don't know what kind of health care they have where you are at. Do they have anything like therapy with psychologists or any mental health doctors or caregivers?
Asia is a really big place, so we don't know how actually dangerous it is where you live. I live in the US, where we don't have wars going on but where people own a ton of guns and like to shoot people a lot. Most other places are actually a lot safer, but if one lives in a neighborhood where there's a lot of gun violence going on, it's not unrealistic to become much more aware of this than if one live in a much more pacific neighborhood. That being said, if you were already afraid of going outside, this sounds like you have an anxiety disorder and it is spreading. I'm not certain I'm getting that right, but if I am right about that, then you really need to get therapy soon before your start getting a whole bunch of phobias, which is no fun. In your case, you've stepped accidentally into a few instances where you heard gunfire near you, so it would be unnatural not to become more aware of your surroundings, but life is always full of risk, we just don't usually think about it much. When you do, it's either an irrational fear, in which case you have an anxiety problem, or you actually live in a place where lots of violence is happening frequently in which case you either move elsewhere or become very aware of your surroundings and take precautions. Which is why I'm focusing on the other statement, which is that you were already afraid of going outside. The way to beat real fears is to calm yourself down as best you can and take what precautions you can without limiting your life to where it's no fun. If the fear is irrational then you have an anxiety problem and that might require professional help to teach you how not to think fearful thoughts. In short, in real danger, one either toughens up and deals or one hides. In danger that isn't all that likely, one works on one's thinking so you don't think like that anymore.