One of the most frustrating things I deal with is that some days I can pick up my guitar and playing is effortless. And then the next day I pick up my guitar and I can't get anything right. It's like my fingers just don't want to obey.
It makes practice difficult because I think I'm making progress and then I lose a whole day.
I don't know if the best thing to do is to just step away and come back later or just push through it.