The ideas are brewing in your head by the dozen?
One pops up in your head for a few minutes and then some other idea takes over?
The left-overs of the first one and the freshly cooked mixture of the next results in incoherence?
Welcome to normalcy! You are not alone. Happens to almost everybody. This is the human mind. We have to train it to think about one thing at a time otherwise it wanders in all directions. It takes a lot to be a focused person.
I can’t stress the importance of jotting down whatever comes to your mind. A phrase or a word can evolve into a complete story. Whatever comes to your mind, write it down. If you can’t move beyond that one phrase right away, trust me.. you will someday. Don’t pile ideas into your head but file them away.