My bad day

I had a bad day, and strange day. First I speak with my mother about my lessions, I had 5 lessions. I went to the gym for practice boxing. I started as a normal day, streching and running, my teacher said: "go to the bag and do one and two for 3 minutes". I started and at the minute 1 nothing happens, but suddenly I see the bag of 75 kg falling. The chain hit me and i saw my head with a lot of blood and the floor with a puddle of blood. The teacher took me to the hospital, I was dizzy and losing blood, I did to emergency and i found my father, he was waiting me at hospital, I have 1 point in the head and some scratches in the head, but the chain hit me very strong and I don't know why the chain fell.