It can be due to some viral skin exanthema, allergic reaction or pityriasis rosea. Pityriasis rosea is a common human skin disease which presents as numerous patches of pink or red oval rash. The rash may be accompanied by low-grade headache, fever, nausea and fatigue and sometimes by itching.
No treatment is usually required. In most patients, the condition lasts only a matter of weeks or months(upto six months)
I suggest you to get the diagnosis confirmed from a dermatologist. I hope it helps. Take care and regards.