Suggest Treatment For Itchy Bumps On The Left Arm

My 15 y.o. daughter started having sudden clusters of itchy bumps on her left arm yesterday morning. Since that time, there have been random spots on her upper back, a few on her lower back, legs, neck, and face. I took her to her primary care physician yesterday and they had no idea what it was. She even broke out in 5 new spots just while we were sitting in the dr. s office! They have referred us to a dermatologist, but that apt is not until next week. We ruled out flea bites, bed bugs, and other insect bites. The randomness is what is causing us to scratch our heads.