I've had one (I assume it is one) annoying me for at least a month now, if not more. It is not a "normal" floater like I've always had, it is darker, much smaller and more circular in shape compared to others.
I thought it was something to do with my contact lenses so I bought eye wash solution and washed out my eye and lenses numerous times but it is still there. Whatever way I move my eye, it's always there floating around after it!
After reading this thread, it really sounds like I should have it checked out?