Spiralling with worry for 3.5 year old

[scaredandspiralling]

I know I should post this in 'child development' but that board is so quiet and I'm really hoping for some responses, please.

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 but 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.

@Aberdeenusername or grasping for straws would make more sense. Brain is scrambled today.

She could be an early developer of an internal monologue. It takes practice to internalise speech and may start with roll play and chatting to yourself. Less than half the population have an internal monologue and it is connected to IQ.
DS was quirky and big into roll play with his dinosaurs at that age. Our internal monologue allows us to process our day and our interactions.
Maybe talked to her about her roll play. It’s a common age to have imaginary friends. DS had an imaginary friend, a full sized triceratops, I once asked if he had his seatbelt on in the car, DS looked at me, rolled his eyes and said “don’t be silly mummy, he doesn’t fit”. I asked how he was going to get to school and was told that he used a motorbike.
It is possible your DD is just playing out what’s going on in her mind. By engaging you may find that she has a lot going on.
DS, it turned out , was just bright with a great imagination. He has learned how to keep his internal monologue to himself but still enjoys the odd quirky conversation because he knows that I have an overactive internal monologue.

Thanks @Angrymum22 your boy sounds fab!

I’d really love to engage with her on it and really try, but when she’s in that zone she is completely impossible to get through to. It’s like her usual self is not there and it’s really horrible.

She sounds like my DS2...Will use the toilet fine at nursery but often gets cross if I suggest it at home, plays a lot of role play...regularly refers to himself as "park ranger LB" (trex ranch character), and enjoys jumping off the coffee table over and over until I tell him off. He just seems like a typical three year old to me!