Hello,
From the photo the rash is appearing a little brownish and from the symptoms erythrasma needs to be ruled out. Erythrasma is a chronic superficial infection of the intertriginous areas of the skin.It is true that groins are effected but the typical appearance is well-demarcated, brown-red macular patches. The skin has a wrinkled appearance with fine scales.
It has to be differentiated from contact dermatitis, psoriasis, sweat dermatitis and fungal infections which may mimic it. Wood lamp examination and gram staining are the tests for its diagnosis.
So nothing can be confirmed without examination. I hope it helps. Take care and regards.