Hello,
I cannot confirm anything without examination but it can be due to jock itch,contact dermatitis,sweat dermatitis,heat rash or intertrigo.
Wash your groins and scrotum daily with a mild soap like dove and then dry thoroughly by pat drying,not rubbing. A hairdryer is useful if you have hairy groins.Also wear cotton underwears and change them twice a day.Also apply local antifungal cream(terbinafine, clotrimazole, econazole, ketoconazole, miconazole) which is available over the counter.
If still the symptoms do not improve then pls get a clinical examination done by a dermatologist.Other possibilities have to be ruled out.
I hope it helps.Take care and pls do keep me posted on how you are doing or if you have any additional queries.Kind regards.
Forget the different diagnosis, apply vaseline only,no dettol no steroid cremes please.
Also, I forgot to mention that when I look at it, it seems almost glossy and shiny. I'm really starting to worry as there are many different "diagnoses" on the internet, from eczema to some chronic diseases.