GOLF, a game I can't understand

All of a sudden, in the middle of a game, I don't seem to be able to swing correctly. Just a few hours ago, I shot 39 on the first nine, and yet I"m struggling to even get a par on the second nine. My stance seems OK, weight distribution, OK, Back swing, OK, follow through,OK, ball strike....SUCKS. In the end, I shot 45 on the second nine. That's twelve over. Yup, still below my handicap of 14, but I could easily shot 6 over 18 if I could be more consistent..NEXT TIME