Suggest Medication For Viral Infection, Itchy Rash On Chest, Genitals And Face

My 3 year was diagnosed last wednesday with a viral infection ,no antibiotics required. But his not getting any better. He has a itchy rash on his chest , genitals and face and his tongue is swollen and his in alot of discomfort and pain. im giving him calpol and nurofin as recommended but its not getting any better. I ve starting giving him zirtec also for itch.