so i was playing part of song yesterday to near perfection. today i was practicing it again and my timing is off, and it sounds a lot sloppier. this seems to happen to me every once in awhile, but once i get over the struggle i seem to get it down.
Every little while i pick up my guitar and start playing, but i just have these off days where i cant play anything, i think i know what you're feeling
i usually practice the bits that make me go of timing more often than the bits that do, so there more clearer to you and less tricky.
Inconsistency? Yeah, I get it too now and again and it's ****ing frustrating as hell. Some days I feel as if I can't hold the pick correctly! It's all in the state of mind
Yep, that happened to me at a gig once lol I had to improvise a **** solo.

We got boo'd off the stage
"You have brains in your head,
You have feet in your shoes,
You can steer yourself,
any direction you choose,
You're on your own,
And you know what you know,
And YOU are the one who'll decide where to go."

- Dr. Seuss
Yeah, it happens. Just take extra time to warm up for about 30 minutes then leave for an hour then come back. It usually helps me out. My case is usually my fingers are very stiff, but sometimes your case is the same way. If nothing comes out of whatever you try, I'm not too sure what to tell you other than there's always tomorrow. (Which isn't the best advice)