My ten year old son keeps having night terrors and i am not sure how to help him. Advise?

Ok my son has been having night terrors for about a month or so, and me and my husband are not sure what to do. I mean we have tried talking to him soothingly,tried just watching him but he got a concussion because he hit his head super hard. We are not sure what to do with him, we know he is having one because we hear this blood curdling scream from him. And then he just crys and crys and then he just falls asleep. Advise?