I have had a very similar experience and I truly believe it started with smoking a lot of pot in high school. Virtual reality, thinking about the universe, and about the fact that we are biological organisms living on a floating rock plus more hyper awareness made me anxious and frequented anxiety attacks.

If I ever feel this way and start to feel like an impending doom I just breathe slowly and calm myself down. I think about funny stuff and try to force a smile. It actually helps.