Hello,
I cannot confirm anything without examination but it can be contact dermatitis, hives, sweat dermatitis or heat rash. Please keep the area clean and apply some topical antiseptics. Also wear loose-fitting cotton clothing and use an antibacterial soap or mild soap like dove. Avoid any kind of cosmetics. Topical zinc oxide cream like Desitin or calamine are very helpful. Application of mild steroid cream like dermacort also helps. In case the symptoms persist then consult a dermatologist in that case so as to confirm the diagnosis. Seborrheic dermatitis is a common skin condition that causes flaky,dry, white to yellowish scales to form on oily areas of the body. It is usually caused by overgrowth of Malassezia furfur.
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.
And how can you tell the difference between something that is just a rash/allergen/dry skin and something like seborrheic dermatitis?