Is it normal to be afraid of extreme density?

Crazy... I get this feeling when I'm awake sometimes that happened in a dream once before. I dunno how to describe it other than the air around me, or atmosphere feels like I'm being pushed in softly but firmly from all directions, like an all round pressure, things start to sound weird, you could say more clearly but with an echo, i feel slightly displaced and panicked, like in slow motion but my mind racing, thinking really quickly... Sort of in limbo. The first time it ever happened was in a dream as i said, it was just a picture dream, a still of a dark, wet ally with garbage cans in great detail... Not like my other dreams which seem to be soft and sort of fuzzy. I felt this dense pressure that made me feel alot smaller than i was, then lots of low echoing noises overlapping and a slight feeling of dread. Then i woke up. I only ever had the dream once, but get the same sort of feeling when I'm awake sometimes, not very often and not as strong. Normally when I'm on my own, being idle and not really thinking of much, i feel it come, then i know its there, then i feel it go, it feels like euphoria, but not a good euphoria... Its weird:/