Sarah’s son came home from high school more than a year ago upset about being bullied. “He came in tears, (saying) ‘they’re calling me a name and someone’s impersonating me,’’ she said in an interview last month. But the name-calling didn’t happen in the hallway or even in-person. Instead someone created an Instagram account online using a taunting nickname, according to Sarah. That’s when her “nightmare with Instagram” began.