Possible wacked Brother?

I woke up one time in the early morning and thought i felt somebody touching me but was too tired to think anything of it sothen i went back to sleep. a little while later i woke up and new someone was touching me. And i felt them going near my so i got rlly nervous and i turned over and pretended to be asleep. so i heard the person go under my bed and looked to c hu it was. i saw my little brothers arms sticking out!!! i dont no wat to do- shud i tell my paremts and get him in major trouble because maybe he needs help- or not say anything? im a lil worried though that he may have tried touching me in other places.... and i didnt feel anything or didnt wake up!!! im sickened to my skin by this!!! Please HELP!!!