Hello,
It can be due to viral rash, allergic reaction or hives. You should also maintain hygiene and try to keep the area clean and dry. Also use an antibacterial soap or mild soap like dove. You can also use a barrier cream with zinc oxide paste or calamine lotion or a mild steroid cream like dermacort on the rash. For the itchiness, you can take some antihistaminic like Benadryl or Claritin.
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.