Hilsometimes rash on the chest and back in pityriasis rosea
is preceded by staphylococcal infection
like cold and cough.it is presented as herald patches ie erythematous annular lesions with peripheral scalling all are of same size but one of them is bigger which is called mother patch.
It can be cured by atarax
25 mg at night.antibiotic like althrocin 500 mg thrice daily and application of calamine
lotion at day time and application of flutivate ointment in the night can cure it