clutch problems

[240sxs1377]

ok here is the problem i was auto xing and during one of the laps my clutch pedal got extremely hard and i couldnt put it into gear. so i coasted off the course and today got to look at it in more detail. when i push in the pedal the slave cylinder works so i am thinking that is somthing with the inside the bell houseing or would this be somthing else. please respond asap because this is my daily driver.