Wow, you've just described my current state of being. I literally froze up mentally last weekend because I had too many things on my mind. Things related to learning/projects/ideas. I kept jumping between them, like a processor performs context switching, but a lot less successfully. It was like bouncing a ball between two walls, and slowly making the gap smaller. The ball's bounces increase exponentially until it cannot anymore. It's at this point you've crashed.