Thanks for the query,
You might have developed fungal infection
The area around anus is very moist and is prone to develop these infections.
The darkening can be due to post inflammatory hyperpigmetation.
you can use a skin lightening cream.
Treatment can be with oral antifungals as well as with topical antifungals.
Various antifungal powders like candid
These can help reduce the moisture as well as control the infection.
Please dont use hydrocortisone
, it is a steroid
and can worsen your condition
Please meet a dermatologist
for exact diagnosis.
Let me know if you have any other doubt.
you can ask a direct question to me on this forum, following the below link.