Sudden change in perception? What is it?

Multiple times a day I feel like a switch has been flipped in my brain and my perception changes in an instant. For example, I felt this today while having lunch and suddenly was hyperaware that I was eating and for some reason it felt so odd and scary. Like I'm suddenly in a video game. Is that part of dissociation? Or is it an adrenaline surge? It's making me feel insane.