That happens when a person rushes through in writing the first chapter, when you still have a vague idea of the main plotline in your head.Not saying that it might have happened to you, but that awful feeling came up after I wrote the first chapter of my discarded fic, Shark Wars.
If you can't describe what's happening, I've found that reading a chapter of your favourite book helps. Reading books gets you into the writing mood, allowing you to describe things more efficiently. Another thing that may be a problem is that you may have been forcing yourself to write. Just relax. Time will come when the brain will feel like writing again.