Thank you for your query on Healthcare Magic.
This type of rash
with foul smelling occurs in fungal infections.
In areas where there is moisture due to excessive sweating
, the fungus will grow and cause skin infections.
I suggest you to wear loose clothes for good aeration.
And local application of an anti fungal agent thrice daily is required to treat the infection.
Therefore I suggest you to consult the dermatologist
for examination and for prescription of medication.
Hope I have answered your query.