I have a 3 yrs 5 month old daughter. She was six weeks premature but no major health concerns, neurotypical older brother (6). Attends nursery four days a week. She's always been a bit of a little weirdo in some ways, but we had no major concerns for her development. She's a lot more shy than her brother and very self-contained, can play by herself very happily for ages, but hit her milestones normally, settled at nursery, starting to play more with other children, speaking fine. She was showing a slight interest in potty training, finally.
But this last three or four weeks, we've noticed a huge change in her. She's started running up and down the room over and over again. She makes noises sucking her teeth, like a tic. No interest in potty training and she screams if we suggest it. She's enormously 'in her own head', having imaginary conversations (out loud) between different characters what feels like all the time - she's always done this a bit and it seemed a good sign of imaginary play, but now it's constant and difficult to get her proper attention. She does still want to play with us, but always in role-play, e.g. "you be Ryder, I'll be Chase", and she keeps this up for ages, even as soon as she wakes up, and uses it to say what she wants, e.g. "let's go downstairs, Ryder."
Her eye contact is fine, she can talk about her emotions (e.g. "he's making me upset!"), and nursery say they don't have any concerns, but have noticed the behaviours we've described.
We've made an appointment to speak to the health visitor but that's not for a couple of weeks and I'm spiralling. I feel like I'm losing my little girl. I think back to the way she was engaging with us only a few weeks ago and I want to cry.
Is this how autism presents? Would it be so sudden like this? If not that, then what?
Please help.