Viral Rash

I woke up to my son with this rash all over him. He's had it for a few days. The np at the pediatrician office said this was a viral rash and they said they couldn't give us anything to for him not even topical. I in all honesty think he may have had an allergic reaction to something bc this still hadn't cleared up. Any suggestions on any topical cream I can use without him getting worse