My mom is a social worker in a school and she's seeing the exact same thing. She'd classify OP's kid as having an issue way beyond gender identity, such as social difficulties, abuse at home, bullying. It's not "rapid onset gender dysphoria" in her opinion. It's something that some kids have co-opted to hide bigger problems. There's been so many things in the past that kids have hid behind to mask problems and this is just another thing. In five years, it might be another thing. But gender identity is way more touchy to question than it is to be using the emo subculture to mask self-harm or the WWJD church camp kids to hide depression.

Rapid gender switching/cycling along with self-harm is what usually tips her off. When she asks "Why do you feel like you're -insert gender here- today?", they cannot give her a response.

She does work with kids that legitimately have struggled with their gender through. And when asked about their identity, they have a long spiel to explain how they feel and even if it's a bit shaky, it's more along the lines of being trans AND a teen and not some other issue.