Rash on little one

Hi all, looking for some advice if anyone has any…
My daughter had a rash appear on Saturday morning. It is behind her ears and goes from one side to the other, slightly down the nape of her neck and up into her scalp. We’ve not tried any new allergens, not changed any laundry or hygiene products etc. The rash itself does go down every few hours but she is going MAD scratching it non stop. It’s really bothering her.
She had her 1 year old vaccinations last Tuesday (late due to GP cancelling twice) and I was made aware a rash may appear as a side effect but after lots of researching, all I see is that it should be a ‘spotty’ like rash and should not be itchy.
I’ve no idea if it’s being caused by the vaccines or something totally different but I’m desperate to try and get rid of it and help my poor little girl. I will attach some photos below from when it first appeared - it looks a lot more red and inflamed now. Any advice is massively appreciated!!

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