Hello,
I cannot confirm anything without examination but it can be contact dermatitis,allergies,sweat dermatitis or heat rash.
You may try calamine lotion on the rash. You should also maintain hygiene and try to keep the area clean and dry, wear loose-fitting cotton clothing. Also use an antibacterial soap or mild soap like dove.Avoid deodorant / cosmetics. You can also use a barrier cream with zinc oxide paste or a moisturizing cream applied directly to wet skin after bathing.
If the rash persists then it will be best to get it evaluated from a dermatologist.
Hope it helps.Take care and pls do keep me posted on how you are doing or if you have any additional doubts.
Could be an allergy rash/hives , have you put any new cream on your face new shower gel, shampoo, eaten anything that could cause an allergy. Google it for answers lots on allergies also an allergy froum here on MH