My almost 2 year old started with rash on torso and upper arms and 12 hours later has mild fever, runny nose?
its like reverse roseola.. does anybody have any idea.. she has mild fever 102 runny nose, watery eyes,, and the rash was mildly itchy.. but seems to have dissipated for the most part. she had a rash like this once when she was an infant and i associated it with detergent but she didn’t have the cold to go with it.. never happened again till now but tjis time cold/allergy symptoms.. any advice on what this is? virus or allergies.. i never associated a fever with allergies.. but rash and cold like symptoms make me wonder.. mucus is clear… for now
she hasn’t had anything to eat or drink that is different than usual.. no diarrhea or vomiting either

You really should call the doctor and ask for advice. I don’t consider 102 degree fever necessarily mild. As always, better safe than sorry.