Thanks for the query.
You might have developed fungal infection
Specially candida infection is more common in peri anal area.
Treatment can be with oral antifungals as well as with topical antifungals.
Also use some anti fungal powder.
This will keep the area dry and will also treat the infection.
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.
Wishing you a good health.