Hello,
This skin rash can be due to contact dermatitis, nummular dermatitis or ringworm (fungal infection). Nummular dermatitis is a sort of eczema and allergic reaction is an important cause. Take some antihistaminic like Benadryl or Claritin and apply some calamine lotion on the rash. Also wear cotton clothes and keep the skin sweat free. If the symptoms persist then please get it examined 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 and please do keep me posted on how you are doing.
Looks like a Nummular eczema.