hello docmillerrs, the problem your daughter has could only be a minor one,fungal ring worm
can be diagnosed by examining scales over the rash,under KOH,and there are certain allergic rashes which appear in circular shape,trasient rashes disappear spontaneousely or may need anti histamines
but certain rashes such as Granuloma annulare
has to be evaluated for diabetes,and some vasculitc disorders to be diagnosed, by biopsy.Dermatologist
consultation definitely helps in diagnosis.