Hello,
Welcome to the ehealthforum and I am really glad to help you out. From the symptoms it can be anything like sweat dermatitis, contact dermatitis, eczema, viral diseases or pityraisis rosea. Pityriasis rosea is a common human skin disease which presents as numerous patches of pink or red oval rash on the trunk.
The rash may be accompanied by low-grade headache, fever, nausea and fatigue and itching. My sincere advice is to get it evaluated from a dermatologist.
It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your doctor. I sincerely hope that helps. Take care.