OT: SNG Psychology help...

K so i sit down and plan on playing a good game and i do, i do two tables at the same time and remain focused. I finish ITM on both of them and make a nice profit finishing 1st and 2nd. Now all of the sudden i dont want to play anymore, even though i now have a lot of spare time to play more, i just dont want to play again and perhaps lose money or worse, break even for the day after playing for a few more hours. The only thing that hangs me up is i know i am a winning player at the level i play at, and that the more quality tournaments i get in, the more money i can make. yet i have this uneasy feeling about playing right away again just after a nice win. does anyone else have this problem or do i just need to grow some sack? what can be done?