Some boy ran into me and i fall, i really dont remember what else happened but my shoulder a d upper hand it hurting. what should i do?

Concussion: From the description of the events you sustained a mild concussion. You wouldn't remember how it happened if it were more intense. These can produce a brief blackout, which you might know from witnesses to the event. If you can feel a head injury & otherwise function normally, just take it easy for a few days. Have a friend monitor your activities. If pain continues have it evaluated.