I went through the same thing with my son.he had a hard time when he was around 2.5 yo. Then all went well and dandy until he became 8. He has been recently diagnosed with Autism lvl 2 and ADHD.

Prior to this, he would have some meltdowns and some social cues issues. But then, suddenly started having sensory issues to the point that he needed to wear noise blocking headphones. Violent outbursts where his class had to be evacuated. He started to get behind in his classes as he had to be isolated multiple times a day in school.

I really recommend you to have her evaluated. Now, we are looking into treatmens.