I think my anus is leaking and i'm in horrible pain. what can i do?

See a doctor: There are lots of reasons for this, including a fissure, fistula, abscess, and other anorectal problems. You should see a doctor to differentiate between these and get the treatment you need for your condition.

Should be evaluated: This could be an infection or possibly a tear and should be evaluated. In the meantime you should try a water soluble fiber to soften your stools (konsyl, 1 tbs a day with water)and wash the area twice a day with a hand held shower.