Monstrous sister??

I can't really remember the beginning too well but.... Basically I had to go to school, and it wasn't for normal school I wasn't going to class but I was roaming through the empty halls and in one of the rooms my little sister was in it pretty young about 4-5 (now 13) her finger nails were really long and Mattalic she looked like a porcelain doll in the face with her hair falling out so I ran to my friends house and I ran into one of the rooms in his house I sat in the closet freaking out and I was sitting in there for a while and heard people coming before I hid in the closet I tried to warn everyone about my little sister and after being in the closet for a while the people I heard coming and they slid the door open and they were FBI agents and they said they wanted to take me somewhere and than if wake up.... I know it's not much to get from but I am really curious why my sister was mutilated?...