It Can be due to contact dermatitis or allergic reaction. The other possibilities are of insect bites, scabies, hives or folliculitis skin. Use a mild cleanser with moisturizing properties like Cetaphil. Also use cotton clothes and change the clothes twice if there is any increased sweating. Try keeping the skin free of sweat as far as possible. If the symptoms still persist then you can apply mild steroid. For the itching antihistaminics like Benadryl or Claritin can be taken.
If the symptoms persist then please get an evaluation done 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.