Yes I know I should see the GP 
But she's well and has had this a week now and it seems silly because I'm sure it's nothing....but can't work out what sort of nothing.
Started with discrete small red spots and only a few on her abdomen (front only) and below level of bra. They have increased over two days to cover more but still none on her back or limbs. Last night she came up with a different rash...more like a heat rash with lots more raised smaller spots. Poor girl is mortified at the appearance. The rash is now higher than bra. It doesn't itch and she is well.
No new laundry products. We do swim a lot both in the sea and in a chlorinated pool often using jacuzzi (water is laser treated??) afterwards. I might cut that out to see if it helps.
So do I drag her out of school to wave her spots under a GPs nose who will say heat/viral/allergy...go away and it will get better on its own or will a MN rash guru appear and diagnose for me saving me the waste of time trip