Rash help...

So my daughter has a rash very similar in appearance to heat rash. But, she hasnt been overly warm. She doesnt itch at it. But it seems to have started on her belly. And upper arms... and now is on her upper thighs and chest a bit as well. She doesnt seem phased by it. Most of it is colorless, some a bit red-like.

She has had heat rash before a few times but it's always been after she was sweaty or too warm.

Her diet hasnt changed, meaning nothing new she has tried recently. Our laundry soap hasnt changed...its unscented and for sensitive skin.

I thought dry skin..lotion hasnt helped. I have her a bath with baking soda..ml nothing has helped. It's been about a week on her belly. Her arms had it but my upper arms get it once and while.... could it be mild allergy??? Idk. We cant get into our dr until January so idk what to think in the mean time...