That infamous malady which afflicts the introspective. Most of the world doesn't have a clue about it, unless they run into a problem with their grocery list.
Those of us who write sometimes have problems with the next sentence, paragraph or thought. There are many remedies relied upon by different authors for this malady.
While reading a copy of "Lew Hunter's Screenwriting 434" book, I thought about the phrase he uses to close emails and with which he embellished the cover of this book; "Write on".
All of which led to an impromptu, off the wall mantra:
I Can Write
I Have Written
I Will Write On
Can be chanted, as needed. Use as directed. Not guaranteed to work in all cases. Some people will have side-effects, such as excess verbiage, non-linear thinking and potty mouth.
See a doctor, if blockage continues.
Remember, only you can put words on the page.