Hello and welcome to healthcaremagic I would keep a possibility of Fixed drug eruption. As the name indicates the eruption is fixed in its location. Intake of the incriminating drug causes it to reappear or become prominent. A lot of drugs can cause this kind of eruption e.g commonly used pain killers/antipyretics, antibiotics etc which are commonly prescribed for cold, flu etc in case of children. Therefore carefully checking the history for the drug administered, might incriminate a particular drug which should be avoided. regards