The same thing happened to me with regards to LR. For a few tests after my PS weekend course, I was rocking them, missing only 3-4, per section. Then I think I started getting lazy. I didn't realize this at the time, I only felt frustrated and sick when my scores started going down. When I got 9 wrong on an LR section, I completely felt like I was going to cry. I put the test away and watched tv for a few hours. The next day, I didn't do any LR. I did a RC section and some games, adn I reread through my PS notes and book for LR strategy. Today, I missed 6 total on LR. So I'm back where I need to be. The combination of the break to calm down feelings of frustartion and anxiety, coupled with the fact that I realized I was getting lazy in applying "tests" to discern the right answer and not looking for subtle wording differences all helped pull me back where I need to be.
Now let's just hope I keep stay this calm and collected through the next 2 days of practice/3 prep exams until the real deal Monday.