Tiny gray clouds appearing in my vision?

When I look up at the sky or the road while i'm driving sometimes, I will see what look like a bunch of little grey clouds flying toward my center of focus. it reminds me of looking into a wormhole or something, everything being sucked into the center. it doesn't affect my vision a whole lot, because they're transparent, and they only really appear around my center of focus, so my peripheral vision is fine. is this a danger to the health of my eyes? should I seek medical attention? thank you