Ds2 has raised red spots and some red blotchy patches all over his back. Some of the spots have a white head, but only a tiny head. There are no spots elsewhere on his body, he doesn't have a temperature, and is eating fine.
I've googled some pictured of chicken pox and it doesn't look quite like that (spots/heads are smaller), but it looks nothing like other rash alternatives (measles, german measles etc).
Can't get a doctor's appointment today.