I have been screwing up lately whats wrong with me?

hey guys usauly i think before i act but these past 3 weeks ive really been screwing up and havent been thinking before i act, im getting less than satisfactory grades in school , have been breaking things a lot lately(not dropping but by being pretty stupid none the less ill explain a bit more of this later) and even severly bruised my finger being stupid and playing mercy with freinds. why do you think ive been screwing up and how can i get my act together thanks