This is the fear of impending doom. You know something are about to happen but you have no power to stop it, the only way is to get out but you always find yourself caught up in the accident.
Maybe recently someone or something are causing you stress, you know, but you ignore or unable to act so that problem goes unsolved and it gives you worry.
Or it can be just a fear of water because you can't swim, if you can't breath in the dream maybe you lack oxygen while sleeping. 