I think everyone goes through something like this at times. I know it sounds trite, but its all mental. Take a deep breath and realize that it isn't the end of the world. Once you do that you'll relax and things will flow better. Keep working, but don't force it. If you have to, take a small break to catch your breath so to speak. Go back to your basics in your martial arts and work on those.
Unfortunately it doesn't get any better as you get older.
As long as you don't let things tie you in knots then you'll get through it.