Hello Qqshadow, trigger points can happen when you least expect them to happen, and it may not be one particular thought that can set you off but a series of them that only accumulate and the least can chain react the rest of your thoughts.
Being susceptible before you even go out could be the start, even before you know it and it only takes a small trigger to set them out off and you can only control your mind when you've had help to understand these trigger points and their consequences so you learn that they won't affect you.
If you are seeing someone to cope with these, you could try and write them down, then you can approach each individual, the pros and cons of knowing when they may surprise you and then how to cope with them.
It's so difficult to overcome this by yourself because you tend to avoid the hard decisions, so if you could talk to your doctor, they will set up a plan to help you.
Geoff.