Hi,
This could be an allergic reaction to some unknown substance or dermatitis or eczema or due to sweat or friction.
You need to wash the areas several times with fresh water. Do not use any cosmetic products at the sites, use a medicated sunscreen whenever you go out. Wear lose, comfortable clothes.
Apply calamine lotion at the site of the lesions and see if it helps. You could take some oral antihistamine medications like cetrizine or loratadine. You need to maintain a good personal hygiene .
It would be advisable to consult a skin specialist for your symptoms and a proper clinical examination.
Let us know if you need any other information and post us on how you are doing.
Regards.
Also, I have an appointment to see the doctor on June 4, just nervous to know what it could be before then :)