Welcome to HCM.
It seems to be fungal infection
,increases due to excessive perspiration and inadequate treatment.
Start oral antifungal
like terbinaforce or itraconazole
Take levocetrizine to subside itching.
Apply local cream containing miconazole,neomycin and fluocinolone.
Take proper local care.Avoid tight undergarment.
Get examined by your doctor for proper line of management.