Hello. Thank you for writing to us The type of rash, its distribution and the timing of appearance suggests that it could either be a part of a viral infection/ exanthem Or it could also be a drug induced rash. Exanthema Subitum , caused by Human Herpes Virus type 6 (HHV Type 6), classically presents with rash that appears the day fever subsides. Fever is high grade in Exanthema subitum but as soon as fever subsides rash makes its appearance. Diagnosis is usually retrospective. The rash in Exanthema subitum subsides in another 2 -3 days, without any complications. Another possibility is of course a drug induced skin rash , probably to one of the drugs, that he might have taken for fever. The possibility of drug induced eruption is very likely if he was given an oral antibiotic for what seems like a viral fever. If I was the treating doctor I would have treated him just symptomatically and with a topical soothing lotion e.g calamine lotion, twice daily. You may also add an OTC oral antihistamine e.g cetrizine syp once daily. Regards