It's been a few hours, I hope it hasn't persisted! When I'm having those issues I like to make a list of all of the other things rambling around in my head. Set a 3-5 minute timer and scribble those thoughts down! Then take a short walk around, like 3-5 minutes, come back to your list and write anything else down.

Then go back to your project!

I like to do this any time I start feeling restless or distracted, because that way I get my thoughts out, "make progress" on something else, and then further extrapolate on those thoughts and get some blood flowing. Makes it easier to come back with a clear conscious!