I have experienced this when i got high around 5 years ago. It got much better in few days and i didn't even realize it got completely okay. Stress is one major reason as well as the substances! It feels so scary, like the body is in some other dimension and our consciousness is somewhere else. As if we're inside a bubble that is separate from the body. And we're just floating in a completely unknown place. It surely gives us the hint of the nature of the reality. What we call our body consciousness is a tiny aspect compared to the universal consciousness which is boundless. I experienced it last month while meditating. Nothing is everything. And that non existence, itself is awareness that is what God, or the ultimate is. Everything is within it and everything is itself, just in different forms. I can tell you that me and you, both are one but you might think I'm crazy. But if you go beyond your sense organs and complete stillness of mind, you'll feel something that is eternal. And when do the same, I'll feel the exact same thing. That is our base, it's same for everybody and everything