Such and more.
Everything gets locked up in a seperate container in our little brain. Some for years long. Some just for days. And it takes a tiny trigger to get the box opened and let that all spillover.
Sometimes you know and recognise those memories right away. And other times you are unable to put your finger on what exactly is it. What's about that memory box that starts bothering you in a split second. It makes you uncomfortable. It even makes you cry. At times it makes you start missing someone who has no connection at all to that memory.
A small conversation with a friend did exactly that to me. I feel the discomfort. I feel weird. So much so that I feel physically unwell. I am unable to explain this to myself. I cannot put my finger on what memory that talk triggered.
It's that lost-in-the-woods-without-any-maps feeling.